Lihini is a CEO of an opera house called the 'Lihini's Opera House". It is the only opera house in the region, giving Lihini's Opera House a monopoly position in the market. Each customer's demand curve for shows per year is given by the following: P = 125 - 6Q. The marginal cost of an extra visitor in a show (i.e., of an extra ticket sold) is $20. Lihini is considering a new pricing scheme for her business: a membership fee that allows people to purchase tickets to the shows after which they can purchase as many opera tickets as they wish for $20 each. If Lihini wants to maximize profits, what is the optimal membership fee that she should charge