Answer:
$2.50
Explanation:
If he paid $13.50 for admission and altogether he paid a total of $36 then you would have to subtract 13.50 from 36 which is 22.50, 22.50 is the price he paid for ALL the tickets so to find the price of one you would need to divide it by 9 so 22.50 ⁒ 9 = 2.50