Answer :
For the sake of it c=x
13.50+9x=36
36-13.50=22.5
9x=22.5
22.5/9=2.5
X=2.5
13.50+9x=36
36-13.50=22.5
9x=22.5
22.5/9=2.5
X=2.5
$2.50 , 36-13.50= 22.50 , then divide that by the number of tickets which was 9.