I need help with this c++ question:

Write a program using function protoype, function calling, and function definition called scale_by_two.

a.) The return value should be of double input.

b.) two variables in int main const int(10); int array[size];

c.) using for loop store double value in array: [2,4,6,8,10,12,14,16,18,20]

d.)using another for loop store an alternative double value to array [2,4,12,8,10,24,14,16,36,20]

Side note: The previous solution was great! but i forgot to mention it should have been a function with parameters