An airplane is about to leave the jetway and take off with 50 empty seats. The regular coach fare is $400 for a seat, and the marginal cost of carrying an extra passenger is $30. Forty standby passengers are hoping to get on the flight. If 10 of those seats can be filled for $200, 25 seats can be filled for $100, and 40 seats can be filled at $40, what is the socially optimal fare to charge standby passengers waiting to fill those seats