A monopolist tattoo parlor has as customers both senior citizens and students. There are 100 senior citizens who value a tattoo at $30, and 100 who value it at $40. There are 50 students who value a tattoo at $35, and 200 who value it at $60. The marginal cost of creating a tattoo is constant at the $10. What price should it charge to maximize profit if the tattoo parlor must charge the same price to all customers?