21. The total cost, c dollars, for Main Street Orchestra to perform a concert at Milly’s Auditorium is determined by c = r + 20m, where r is the rental fee, in dollars, of the auditorium and m is the number of orchestra members playing. The Friday night rental fee for Milly’s Auditorium is $500. There will be 30 orchestra members playing in Friday night’s concert. For the total price of exactly 200 tickets to equal the total cost of performing the concert, what should be the price of each ticket?