Lionel uses two functions to model the costs of having a problem diagnosed and repaired by two appliance repair companies. He models the cost, in dollars, of having Phil’s Appliances handle the repair job, requiring x hours of labor, with function p: p(x) = 68x + 81. He models the cost of having Quality Electric handle the same repair with function q: q(x) = 51x + 90. The function_______ represents the amount, in dollars, Lionel will save by having Quality Electric handle an x-hour repair instead of Phil’s Appliances. Lionel will save_____ $ if he uses Quality Electric for a repair needing 2 hours of labor.