Please advise, need help! Thanks!

A firm with market power knows that an individual consumer has the following demand function: Q = 36 - 4P where Q stands for the quantity demanded by one consumer and P stands for the price. Suppose all customers are identical. The cost function for the firm is C = 2Q The firm wants to use a two-part tariff to sell this product. Recall that a two part tariff consists of an entry fee and a price per unit (just like Costco charges a membership fee and then sells products at some price per unit) In order to maximize profits, what price per unit should the firm charge each consumer? (You may assume that if the firm charges the right price per unit, it will also charge the right entry fee, thereby maximizing profits)