Draw a cost curve and using those costs show on your graph using a horizontal demand curve of where the output with a firm in perfect competition (not imperfect competition) will be placed. (Under this Perfect Competitive situation remember that a firm is making a normal rate of profit for the owner to just meet his or her family's obligations and a bit extra in interest) Also, If a firm cannot meet that demand how far down will it allow its price to be before it will have to shut down