Answer: 275 adult tickets and 500 children's tickets were sold.
Explanation:
Let x represent the number of adult tickets that were sold.
Let y represent the number of children's tickets that were sold.
775 tickets were sold for the game. It means that
x + y = 775
If adults tickets sold for 2.50 and children's tickets sold for 1.00 and all the tickets were sold for a total of 1,187.50, it means that
2.5x + y = 1187.5
Substituting x = 775 - y into equation 1, it becomes
2.5(775 - y) + y = 1187.5
1937.5 - 2.5y + y = 1187.5
- 2.5y + y = 1187.5 - 1937.5
- 1.5y = - 750
y = - 750/ - 1.5
y = 500
x = 775 - y = 775 - 500
x = 275