diff --git a/lesson_04/expression/expression_app/src/main/java/com/codedifferently/lesson4/ExpressionCalculator.java b/lesson_04/expression/expression_app/src/main/java/com/codedifferently/lesson4/ExpressionCalculator.java
index bd234deb..f69ee18e 100644
--- a/lesson_04/expression/expression_app/src/main/java/com/codedifferently/lesson4/ExpressionCalculator.java
+++ b/lesson_04/expression/expression_app/src/main/java/com/codedifferently/lesson4/ExpressionCalculator.java
@@ -1,12 +1,25 @@
 package com.codedifferently.lesson4;
 
 public class ExpressionCalculator {
-  /**
-   * Returns the calculation of ((a + b) * c) / d^e
-   */
+  /** Returns the calculation of ((a + b) * c) / d^e */
   public double calculate(double a, double b, double c, double d, double e) {
-    // Implement your code here to return the correct value.
-    return 0d;
+    double output = ((a + b) * c) / pow(d, e);
+    return output;
+  }
+
+  public double add(double a, double b) {
+    double sum = a + b;
+    return sum;
+  }
+
+  public double multiply(double a, double b) {
+    double product = a * b;
+    return product;
+  }
+
+  public double divide(double a, double b) {
+    double quotient = a / b;
+    return quotient;
   }
 
   public double pow(double base, double exponent) {