The OSRAM Lamp Company, estimated the following demand function for its product: Q = 120,000 - 10,000P where Q is the quantity demanded per year and P is the price per lamp. The firm's fixed cost is $12,000 and variable cost is $1.50 per lamp. a. Write an equation for the total revenue (TR) function in terms of Q. (2) b. State the marginal revenue function. (2) c. Write an equation for the total cost (TC) function in terms of Q. (2) d. State the marginal cost function. (1)