Answer:
10.5a + 7c + 3 ---> a adults and c children
From this statement, we can assume that $10.50 is the price for 1 adult ticket, $7 is the price for 1 child ticket, and $3 is the service fee.
For 2 adults + 4 children:
(2 × $10.50) + (4 × $7) + $3 = $52
Ans: $52