Fixed calculate method and ensured all tests pass

Author: Jeremiahwing

lesson_06/expression/.env.test

@@ -1 +1 @@
-HW_VERSION=D
+HW_VERSION=D 

lesson_06/expression/src/expression_calculator.ts

@@ -1,11 +1,25 @@
 export class ExpressionCalculator {
   /** Returns a calculation involving a, b, c, d, and e */
   calculate(a: number, b: number, c: number, d: number, e: number): number {
-    // Implement your code here to return the correct value.
-    return 0;
+    const sum = this.add(c, d);
+    const power = this.pow(sum, e);
+    const product = this.multiply(a, b);
+    return this.divide(product, power);
   }
 
   pow(base: number, exponent: number): number {
     return Math.pow(base, exponent);
   }
-}
+
+  add(a: number, b: number): number {
+    return a + b;
+  }
+
+  multiply(a: number, b: number): number {
+    return a * b;
+  }
+
+  divide(a: number, b: number): number {
+    return a / b;
+  }
+}