5(how many tickets) x 2(cost of one ticket) equals 10. 25(total amount of money)- 10(how much money the tickets cost in total) equals 15(the entry fee)
10 (how many tickets) x 2(cost of one ticket) equals 20. 35(total amount of money)- 20(how much money the tickets cost in total) equals 15(the entry fee)
