diff --git a/MathUtilities.class b/MathUtilities.class
index 4ea9860..8f0b7d4 100644
Binary files a/MathUtilities.class and b/MathUtilities.class differ
diff --git a/MathUtilities.java b/MathUtilities.java
index 7d4f4fc..0336004 100644
--- a/MathUtilities.java
+++ b/MathUtilities.java
@@ -11,7 +11,7 @@ public class MathUtilities {
      * @return sum of `baseValue` and `difference`
      */
     public Integer add(int baseValue, int difference) {
-        return null;
+        return baseValue + difference;
     }
 
     /**
@@ -20,7 +20,7 @@ public Integer add(int baseValue, int difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Long add(long baseValue, long difference) {
-        return null;
+        return baseValue + difference;
     }
 
     /**
@@ -29,7 +29,7 @@ public Long add(long baseValue, long difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Short add(short baseValue, short difference) {
-        return null;
+          return (short) (baseValue + difference);
     }
 
     /**
@@ -38,7 +38,7 @@ public Short add(short baseValue, short difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Byte add(byte baseValue, byte difference) {
-        return null;
+        return (byte) (baseValue + difference);
     }
 
     /**
@@ -47,7 +47,7 @@ public Byte add(byte baseValue, byte difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Float add(float baseValue, float difference) {
-        return null;
+        return (float) (baseValue + difference);
     }
 
     /**
@@ -56,7 +56,7 @@ public Float add(float baseValue, float difference) {
      * @return sum of `baseValue` and `difference`
      */
     public Double add(double baseValue, double difference) {
-        return null;
+        return (double) (baseValue + difference);
     }
 
     /**
@@ -65,7 +65,7 @@ public Double add(double baseValue, double difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Integer subtract(int baseValue, int difference) {
-        return null;
+        return baseValue - difference;
     }
 
     /**
@@ -74,7 +74,7 @@ public Integer subtract(int baseValue, int difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Long subtract(long baseValue, long difference) {
-        return null;
+        return baseValue - difference;
     }
 
     /**
@@ -83,7 +83,7 @@ public Long subtract(long baseValue, long difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Short subtract(short baseValue, short difference) {
-        return null;
+        return (short) (baseValue - difference);
     }
 
     /**
@@ -92,7 +92,7 @@ public Short subtract(short baseValue, short difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Byte subtract(byte baseValue, byte difference) {
-        return null;
+        return (byte) (baseValue - difference);
     }
 
     /**
@@ -101,7 +101,7 @@ public Byte subtract(byte baseValue, byte difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Float subtract(float baseValue, float difference) {
-        return null;
+        return (float) (baseValue - difference);
     }
 
     /**
@@ -110,7 +110,7 @@ public Float subtract(float baseValue, float difference) {
      * @return difference between `baseValue` and `difference`
      */
     public Double subtract(double baseValue, double difference) {
-        return null;
+        return (double) (baseValue - difference);
     }
 
 
@@ -120,7 +120,7 @@ public Double subtract(double baseValue, double difference) {
      * @return division of `dividend` by `divisor
      */
     public Integer divide(int dividend, int divisor) {
-        return null;
+        return dividend / divisor;
     }
 
     /**
@@ -129,7 +129,7 @@ public Integer divide(int dividend, int divisor) {
      * @return division of `dividend` by `divisor
      */
     public Long divide(long dividend, long divisor) {
-        return null;
+        return dividend / divisor;
     }
 
     /**
@@ -138,7 +138,7 @@ public Long divide(long dividend, long divisor) {
      * @return division of `dividend` by `divisor
      */
     public Short divide(short dividend, short divisor) {
-        return null;
+        return (short) (dividend / divisor);
     }
 
     /**
@@ -147,7 +147,7 @@ public Short divide(short dividend, short divisor) {
      * @return division of `dividend` by `divisor
      */
     public Byte divide(byte dividend, byte divisor) {
-        return null;
+        return (byte) (dividend / divisor);
     }
 
     /**
@@ -156,7 +156,7 @@ public Byte divide(byte dividend, byte divisor) {
      * @return division of `dividend` by `divisor
      */
     public Float divide(float dividend, float divisor) {
-        return null;
+        return (float) (dividend / divisor);
     }
 
     /**
@@ -165,7 +165,7 @@ public Float divide(float dividend, float divisor) {
      * @return division of `dividend` by `divisor
      */
     public Double divide(double dividend, double divisor) {
-        return null;
+        return (double) (dividend / divisor);
     }
 
 
@@ -175,7 +175,7 @@ public Double divide(double dividend, double divisor) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Integer multiply(int multiplicand, int multiplier) {
-        return null;
+        return multiplicand * multiplier;
     }
 
     /**
@@ -184,7 +184,7 @@ public Integer multiply(int multiplicand, int multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Long multiply(long multiplicand, long multiplier) {
-        return null;
+        return multiplicand * multiplier;
     }
 
     /**
@@ -193,7 +193,7 @@ public Long multiply(long multiplicand, long multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Short multiply(short multiplicand, short multiplier) {
-        return null;
+        return (short) (multiplicand * multiplier);
     }
     /**
      * @param multiplicand value to be multiplied
@@ -201,7 +201,7 @@ public Short multiply(short multiplicand, short multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Byte multiply(byte multiplicand, byte multiplier) {
-        return null;
+        return (byte) (multiplicand * multiplier);
     }
 
     /**
@@ -210,7 +210,7 @@ public Byte multiply(byte multiplicand, byte multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Float multiply(float multiplicand, float multiplier) {
-        return null;
+        return (float) (multiplicand * multiplier);
     }
 
     /**
@@ -219,6 +219,6 @@ public Float multiply(float multiplicand, float multiplier) {
      * @return product of `multiplicand` by `multiplier`
      */
     public Double multiply(double multiplicand, double multiplier) {
-        return null;
+        return (double) (multiplicand * multiplier);
     }
 }
diff --git a/PredicateUtilities.class b/PredicateUtilities.class
index 64dfa1b..5af8bf5 100644
Binary files a/PredicateUtilities.class and b/PredicateUtilities.class differ
diff --git a/PredicateUtilities.ctxt b/PredicateUtilities.ctxt
index d46571c..e59f256 100644
--- a/PredicateUtilities.ctxt
+++ b/PredicateUtilities.ctxt
@@ -9,7 +9,7 @@ comment2.target=java.lang.Boolean\ isLessThan(int,\ int)
 comment2.text=\n\ @param\ x\n\ @param\ y\n\ @return\ true\ if\ `x`\ is\ less\ than\ `y`\n
 comment3.params=x\ y
 comment3.target=java.lang.Boolean\ isGreaterThanOrEqualTo(int,\ int)
-comment3.text=\n\ @param\ x\n\ @param\ y\n\ @return\ true\ if\ `x`\ is\ greater\ than\ or\ equal\ to\ `y`\n
+comment3.text=\n\ @param\ x\n\ @param\n\ @return\ true\ if\ `x`\ is\ greater\ than\ or\ equal\ to\ `y`\n
 comment4.params=x\ y
 comment4.target=java.lang.Boolean\ isLessThanOrEqualTo(int,\ int)
 comment4.text=\n\ @param\ x\n\ @param\ y\n\ @return\ true\ if\ `x`\ is\ less\ than\ or\ equal\ to\ `y`\n
diff --git a/PredicateUtilities.java b/PredicateUtilities.java
index 4b83a87..d1c1eb3 100644
--- a/PredicateUtilities.java
+++ b/PredicateUtilities.java
@@ -1,4 +1,4 @@
- 
+
 
 /**
  * Created by dan on 6/14/17.
@@ -10,25 +10,38 @@ public class PredicateUtilities {
      * @return true if `x` is greater than `y`
      */
     public Boolean isGreaterThan(int x, int y) {
-        return null;
+       if(x > y) {
+          return true;
+        }else {
+            return false;
+        }
     }
 
+
     /**
      * @param x
      * @param y
      * @return true if `x` is less than `y`
      */
     public Boolean isLessThan(int x, int y) {
-        return null;
+        if(x < y) {
+            return true;
+         }else {
+             return false;
+            }
     }
 
     /**
      * @param x
-     * @param y
+     * @param
      * @return true if `x` is greater than or equal to `y`
      */
     public Boolean isGreaterThanOrEqualTo(int x, int y) {
-        return null;
+        if( x >= y) {
+            return true;
+        }else {
+            return false;
+        }
     }
 
     /**
@@ -37,7 +50,11 @@ public Boolean isGreaterThanOrEqualTo(int x, int y) {
      * @return true if `x` is less than or equal to `y`
      */
     public Boolean isLessThanOrEqualTo(int x, int y) {
-        return null;
+        if( x <= y) {
+            return true;
+        }else {
+            return false;
+        }
     }
     
     
@@ -45,13 +62,13 @@ public Boolean isLessThanOrEqualTo(int x, int y) {
       * @return true
      */
     public Boolean returnTrue() {
-        return null;
+        return true;
     }
 
     /**
      * @return false
      */
     public Boolean returnFalse() {
-        return null;
+        return false;
     }
 }
\ No newline at end of file
diff --git a/StringUtilities.class b/StringUtilities.class
index 71bb6fd..63bf378 100644
Binary files a/StringUtilities.class and b/StringUtilities.class differ
diff --git a/StringUtilities.java b/StringUtilities.java
index b791a2a..12e5cf1 100644
--- a/StringUtilities.java
+++ b/StringUtilities.java
@@ -8,7 +8,7 @@ public class StringUtilities {
      * @return `Hello World` as a string
      */
     public static String getHelloWorld() {
-        return null;
+        return "Hello World";
     }
 
     /**
@@ -17,7 +17,9 @@ public static String getHelloWorld() {
      * @return the concatenation of two strings, `firstSegment`, and `secondSegment`
      */
     public static String concatenation(String firstSegment, String secondSegment){
-        return null;
+        String convert = String.valueOf(firstSegment);
+        String combined = convert + secondSegment;
+        return combined;
     }
 
     /**
@@ -26,7 +28,7 @@ public static String concatenation(String firstSegment, String secondSegment){
      * @return the concatenation of an integer, `firstSegment`, and a String, `secondSegment`
      */
     public static String concatenation(int firstSegment, String secondSegment){
-        return null;
+        return "firstSegment + secondSegment";
     }
 
     /**
@@ -34,7 +36,9 @@ public static String concatenation(int firstSegment, String secondSegment){
      * @return the first 3 characters of `input`
      */
     public static String getPrefix(String input){
-        return null;
+        
+       
+        return input.substring(0,3);
     }
 
     /**
@@ -42,7 +46,7 @@ public static String getPrefix(String input){
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return null;
+        return input.substring(input.length() - 3, input.length());
     }
 
     /**
@@ -51,7 +55,9 @@ public static String getSuffix(String input){
      * @return the equivalence of two strings, `inputValue` and `comparableValue`
      */
     public static Boolean compareTwoStrings(String inputValue, String comparableValue){
-        return null;
+         if (inputValue==comparableValue) { 
+             return true;
+            }else {return false;}
     }
 
     /**
@@ -59,7 +65,8 @@ public static Boolean compareTwoStrings(String inputValue, String comparableValu
      * @return the middle character of `inputValue`
      */
     public static Character getMiddleCharacter(String inputValue){
-        return null;
+        int mid = (inputValue.length()-1)/2;
+        return inputValue.charAt(mid);
     }
 
     /**
@@ -67,7 +74,8 @@ public static Character getMiddleCharacter(String inputValue){
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return null;
+        String[] words = spaceDelimitedString.split(" ");
+        return words[0];
     }
 
     /**
@@ -75,7 +83,8 @@ public static String getFirstWord(String spaceDelimitedString){
      * @return the second word of a string delimited by spaces.
      */
     public static String getSecondWord(String spaceDelimitedString){
-        return null;
+        String[] words = spaceDelimitedString.split(" ");
+         return words [1]; 
     }
 
     /**
@@ -83,6 +92,9 @@ public static String getSecondWord(String spaceDelimitedString){
      * @return an identical string with characters in reverse order.
      */
     public static String reverse(String stringToReverse){
-        return null;
+        String reverse = " ";
+        for (int i = stringToReverse.length() - 1; i >=0; i --) {
+            reverse += stringToReverse.charAt(i);
+        } return reverse;
     }
 }
diff --git a/package.bluej b/package.bluej
index 5ded697..0a01f12 100644
--- a/package.bluej
+++ b/package.bluej
@@ -1,20 +1,20 @@
 #BlueJ package file
-editor.fx.0.height=0
-editor.fx.0.width=0
-editor.fx.0.x=0
-editor.fx.0.y=0
-objectbench.height=129
-objectbench.width=531
+editor.fx.0.height=721
+editor.fx.0.width=800
+editor.fx.0.x=240
+editor.fx.0.y=23
+objectbench.height=164
+objectbench.width=837
 package.divider.horizontal=0.6397146254458977
-package.divider.vertical=0.8697318007662835
-package.editor.height=901
-package.editor.width=727
-package.editor.x=1440
-package.editor.y=0
-package.frame.height=1080
+package.divider.vertical=0.6138763197586727
+package.editor.height=400
+package.editor.width=735
+package.editor.x=100
+package.editor.y=23
+package.frame.height=721
 package.frame.width=861
 package.numDependencies=0
-package.numTargets=6
+package.numTargets=9
 package.showExtends=true
 package.showUses=true
 project.charset=UTF-8
@@ -27,7 +27,6 @@ target1.height=50
 target1.name=PredicateUtilities
 target1.showInterface=false
 target1.type=ClassTarget
-target1.typeParameters=
 target1.width=130
 target1.x=280
 target1.y=120
@@ -35,39 +34,55 @@ target2.height=50
 target2.name=StringUtilitiesTest
 target2.showInterface=false
 target2.type=UnitTestTargetJunit4
-target2.typeParameters=
 target2.width=140
 target2.x=490
 target2.y=70
 target3.height=50
-target3.name=MathUtilities
+target3.name=TestMultiplication
 target3.showInterface=false
-target3.type=ClassTarget
-target3.typeParameters=
-target3.width=100
-target3.x=60
-target3.y=150
+target3.type=UnitTestTargetJunit4
+target3.width=140
+target3.x=70
+target3.y=60
 target4.height=50
-target4.name=PredicateUtilitiesTest
+target4.name=TestDivision
 target4.showInterface=false
 target4.type=UnitTestTargetJunit4
-target4.typeParameters=
-target4.width=160
-target4.x=260
-target4.y=50
+target4.width=100
+target4.x=170
+target4.y=120
 target5.height=50
-target5.name=StringUtilities
+target5.name=TestSubtraction
 target5.showInterface=false
-target5.type=ClassTarget
-target5.typeParameters=
-target5.width=110
-target5.x=500
-target5.y=130
+target5.type=UnitTestTargetJunit4
+target5.width=120
+target5.x=10
+target5.y=210
 target6.height=50
-target6.name=MathUtilitiesTest
+target6.name=MathUtilities
 target6.showInterface=false
-target6.type=UnitTestTargetJunit4
-target6.typeParameters=
-target6.width=130
-target6.x=50
-target6.y=90
+target6.type=ClassTarget
+target6.width=100
+target6.x=60
+target6.y=150
+target7.height=50
+target7.name=StringUtilities
+target7.showInterface=false
+target7.type=ClassTarget
+target7.width=110
+target7.x=500
+target7.y=130
+target8.height=50
+target8.name=PredicateUtilitiesTest
+target8.showInterface=false
+target8.type=UnitTestTargetJunit4
+target8.width=160
+target8.x=260
+target8.y=50
+target9.height=50
+target9.name=TestAddition
+target9.showInterface=false
+target9.type=UnitTestTargetJunit4
+target9.width=100
+target9.x=170
+target9.y=180