5 children tickets and 2 adult tickets were bought
Explanation:
Let the no. of child tickets be 'c'
Let the no. of adult tickets be 'a'
Total tickets = 7
Total cost = $31
Cost per adult ticket = $8
Cost per child ticket = $3
The equation ,
3c + 8a = 31
a + c = 7
a = 7 - c
3c + 8a =31
3c + 8(7-c) =31
3c + 56 - 8c = 31
-5c = -25
c = 5
a = 7 -5
a = 2
5 children tickets and 2 adult tickets were bought