Write three independent functions to handle the problem of calculating the bill at a coffee shop. The first prompts for all three input values (the quantities of the items sold) and gives them back to the caller; the second calculates the extended line amounts, subtotal, tax, and grand total of the bill; and the third prints the bill itself. The tasks done by the functions MUST be broken up along these lines. Write a main() function that declares local variables for the values you need to manipulate and passes them to the functions as needed. You may not use any global variables for this assignment. All variables MUST be declared within functions. Global constants are O.K.