Added lesson06 expression calculator and env

Author: Ananatawa

lesson_06/expression/.env.test

@@ -1 +1 @@
-HW_VERSION=your assigned version here
+HW_VERSION=C 

lesson_06/expression/src/expression_calculator.ts

@@ -2,10 +2,29 @@ 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 exponent = this.pow(d, e);
+    const division = this.divide(a, b);
+    const multiplication = this.multiply(c, exponent);
+    const result = this.add(division, multiplication);
+    return result;
   }
+  // Function to implement: a / b + c * Math.pow(d,e)
 
   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;
+  }
+  
 }