Answer: he bought 2 adult tickets and 7 children tickets.
Step-by-step explanation:
Let x represent the number of adult tickets that he bought.
Let y represent the number of children tickets that he bought.
He brought some adult tickets and some children tickets for a total of 9 tickets. This means that
x + y = 9
The adult tickets cost $10 per ticket and the children tickets cost $8 per ticket if he spent a total of $76, it means that
10x + 8y = 76 - - - - - - - - - - - -1
Substituting x = 9 - y into equation 1, it becomes
10(9 - y) + 8y = 76
90 - 10y + 8y = 76
- 10y + 8y = 76 - 90
- 2y = - 14
y = - 14/ -2
y = 7
x = 9 - y = 9 - 7
x = 2
