The long-run total cost function for producers of mineral water is TC(Q) = cQ, where Q is

Question:

The long-run total cost function for producers of mineral water is TC(Q) = cQ, where Q is the output of an individual firm expressed as thousands of liters per year. The market demand curve is D(P) = a − bP. Find the long-run equilibrium price and quantity in terms of a, b, and c. Can you determine the equilibrium number of firms? If so, what is it? If not, why not?