The market demand for a particular good is described by the equation: P = 60-0.5Q. There is one firm in this market; its marginal cost is constant at $15 and there is no fixed cost. Consider that consumers are identical, and each individual demand is described by the equation: P = 60 - Q. The firm is currently charging an access fee and then a price per unit for each quantity sold. [a.] What are the firm's profit-maximizing quantity, the access fee charged, and the price per unit charged [b.] What is the firm's profit at the prices it charges?