Suppose there is a firm producing in a competitive market where the market equilibrium price is $15. Suppose further that at MR = MC, the output of the individual firm is 100 units, and at this level of production average total costs are $12.

This firm will price their product at $ what price?per unit and make loss or profit?

of what $ in the short run. In the long run, firms will exit or enter the market push profits either above, or to or below zero.