c++

This question has 2 parts: A function definition and a main function with a function call. PART 1: Write a function definition for a function that takes one argument of type double. Inside the function declare, prompt and read a double from the keyboard. Subtract the parameter double from the double that was entered by the user. The function will return the result, the number entered by the user minus the parameter value. PART 2: Write a main function with a function call to the function defined above. Be sure to declare variables and assign values as needed