Answer:
3 adult tickets and 5 children tickets.
Explanation:
Make a chart:
1 adult + 7 children = 1(5)+7(3) = 26
2 adults + 6 children = 2(5)+6(3) = 28
3 adults + 5 children = 3(5)+5(3) = 30
4 adults + 4 children = 4(5)+4(3) = 32
5 adults + 3 children = 5(5)+3(3) = 34
6 adults + 2 children = 6(5)+2(3) = 36
7 adults + 1 child = 7(5)+1(3) = 38
The answer in bold is the only one that leads to $30, therefore he bought 3 adult tickets and 5 children tickets.