a. P=f(Q): P=215-7Q MR=f(Q): MR=-7 ATC=f(Q, Q): ATC=2700/Q-7Q AVC=f(Q, Q): AVC=2.7Q-7Q MC=f(Q, Q): MC=-14Q 7Q b. Profit-maximizing price and quantity: P = $159 and Q = 100 c. Total profit earned: $17,900 d. The Lerner index is calculated as (P-MC)/P. This is equal to (159-14Q 7Q)/159. When Q=100, the Lerner index would be 0.1264. This indicates that the market is moderately competitive