Complete the following steps: Write a C++ statement that includes the header file iostream. Write a C++ statement that allows you to use cin, cout, and endl without the prefix std: Write C++ statement(s) that declare the following variables: num1, num2, num3, and average of type int. Write C++ statements that store 125 into num1, 28 into num2 and -25 into num3 Write a C++ statement that stores the average of num1, num2, and num3, into average. Write C++ statement(s) that output the values of num1, num2, and num3