Part A: The table does not represent y as a function of x. We can not input 1 and get 4 and 2 as outputs ( or input 3 and get 12 and 6 as outputs ). Part B : f (120) is a cost for renting a peddleboat for 120 hours; f (120) = 20 + 10 * 120 = 20 + 1,200 = 1,220.