adding demo code for arrow functions

Author: aaronpowell

15-arrow-functions/demo.js

@@ -0,0 +1,8 @@
+const add = (a, b) => a + b;
+console.log(add(1, 2));
+
+const subtract = (a, b) => {
+  const result = a - b;
+  return result;
+};
+console.log(subtract(1, 1));