Type the correct answer in each box. Use numerals instead of words. If necessary, use / for the fraction bar(s).
Charlie runs a book rental business. He currently charges $3 per book and rents out an average of 38 books a day.
According to a study, for every 50 C increase in rental price, the average business can 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 500 price increases.
b(x)= -_x^2+_x+_