charlie runs a book rental business. He currently charges $3 per book rents out an average of 38 books a day. according to study, for every 50cent increase in rental price, the average business can be expect to lose 4 rentals a day. complete the equation that models this scenario, where b(x) is the revenue generated and x is the number of 59 cent price increases. b(x) = _ x^2 + _ x + _ (fill in the blank)