A 10% booking fee is added to the ticket price (I'm guessing 10% is added for each ticket)
Find 10% of the adult and child ticket:
10% of 15 = 1.5
10% of 10 = 1
find the total price for the 4 adult tickets he buys and 2 child tickets:
(15 +1.5) × 4 = 66
(10 + 1) × 2 = 22
66 + 22 = 88
1.5% will then be added if he lays by credit card :
1.5% of 88 = 1.32
total :
88 + 1.32 = 89.32
He pays a total of £89.32