I can solve, I just need help setting the question up. Thank you

A Broadway theater has 500 seats, divided intoorchestra, main, and balcony seating. Orchestra seats sell for $40, main seats for $25, and balcony seats for $20. If all the seats aresold, the gross revenue to the theater is $13,100. If all the main and balcony seats aresold, but only half the orchestra seats aresold, the gross revenue is $11,100. How many are there of each kind ofseat?