In a baseball stadium, there are three types of seats available. Box seats are $9, reserved seats are $7, and lawn seats are $5. The stadium capacity is 3900. If all the seats are sold, the total revenue to the club is $27,660. If one half of the box seats sold, one half of the reserved seats are sold, and all the
lawn seats are sold, the total revenue is $17,230. How many of each kind of seat are there?
There are …………. box seats.