You are a newly appointed regulator for a monopoly firm in your state. To work out what the regulated price should be for the firm's product, you first need to work out what the firm's demand curve looks like.

When the firm charged a price of $115 dollars it sold 5600 units of its product. When it charged a price of $120 dollars, it sold 4800 units of its product

Using this information, estimate the firm's demand curve: