Assume that postage rates are $0.44 for the first ounce, plus $0.20 for each additional ounce, and that each letter carries one $0.44 stamp and as many $0.20 stamps as necessary. Graph the function f that models the number of stamps on a letter weighing x ounces over the interval (0,5].

I need the function that this word problem makes. I really need step by step instructions but, I have no idea how to do it. Please help.