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Let x be the number of $1.50 tickets for 1 adults and one child.
Let y be the number of $2 tickets for 2 adults and one child.
Then the number of $1 tickets for single adult is (62-x-2y).
Then you have these two equations:
x + y = 32 (1) (counting children)
1.5x + 2y + (62-x-2y) = 69 (2) (counting money)
Simplify:
x + y = 32, (3)
0.5x = 69-62 = 7 (4)
Simplify again:
x + y = 32, (5)
0.5x = 7. (6)
It is clear now from (2) that x = 2*7 = 14.
Then from (1) y = 32 - x = 32 - 14 = 18.
Answer. 14 $1.50 tickets; 18 $2 tickets; and the number of $1 tickets is 62-x-2y = 62-14-2*18 = 12.
The lesson to learn from this solution:
I wanted, most of all, to reduce the problem to 2 equations and avoid having 3 equations.
And I succeeded in it.