Answer:
He bought 9 children's tickets.
Step-by-step explanation:
Let x be the no. of children's tickets.
Let y be the no. of adult tickets.
We are given that Ed bought 15 tickets
So, [tex]x+y=15[/tex] --1
Cost of 1 child ticket = $3
Cost of x no. of children's tickets = 3x
Cost of 1 adult ticket = $5
Cost of y no. of adult's tickets = 5y
Since we are given that total cost is $57
So, [tex]3x+5y = 57[/tex] --- 2
Solving 1 and 2
Substitute the value of y from 1 in 2
So, [tex]3x+5(15-x) = 57[/tex]
[tex]3x+75-5x = 57[/tex]
[tex]75-2x = 57[/tex]
[tex]75-57=2x[/tex]
[tex]18=2x[/tex]
[tex]\frac{18}{2}=x[/tex]
[tex]9=x[/tex]
Hence he bought 9 children's tickets .
