Given a firm’s marginal cost curve MC, average total cost curve ATC, and market price P, the firm’s profit can be measured by the area of the rectangle with length Q* and height (P – ATC*).(a) A firm facing a market price above its average total cost curve at Q* will earn a positive economic profit, π > 0.(b) A firm facing a market price equal to its average total cost at Q* earns zero economic profit.(c) A firm with average total cost above the market price, at Q*, will earn negative economic profit (loss), π < 0.