The demand function for a textbook is given by p =500 - where x is the number of textbooks that can be sold at a price of $p per textbook. a. Rewrite the demand function as . Identify the slope and interpret the value. * = f(P) b. Sketch the demand function. c. Find the revenue function R =R(x) d. If each textbook is obtained from a supplier at a cost of $100 per book, find the profit function. e. Find the profit when 600 books are sold