15. A firm”s economic profit is equal to its total revenue (TR) minus its total cost (TC). Restate the economic profit equation using quantity (Q), Profit= Quantity (Price- Average cost) price (P), and average cost (AC). If P falls below AC, what is the result for the firm? Firm loses money 16. In the late-19th century, both firms and markets expanded. How did this impact competition in many markets?