EXERCISE 3: 1. Write a C program to calculate and display the sum of two numbers x and y. The result is stored in z. Your program should prompt the user to enter the two numbers and then call a function named summation to add the two numbers. The addresses of x, y, and z must be passed as parameters to the function summation. 2. Modify your program to include a function named avg which calculates and returns the average of the two numbers. The addresses of x, y, and z must be passed as parameters to the function avg. 3. Modify your program to include a function named maxm which finds and returns the max of the two numbers. The addresses of x, y, and z must be passed as parameters to the function maxm