Answer: the cost of an adult ticket is $9.
The cost of a child's ticket is $13
Step-by-step explanation:
Let x represent the price of one adult ticket.
Let y represent the price of one student ticket.
On the first day of ticket sales, the school sold two adult tickets and three students tickets for a total of $57. It means that
2x + 3y = 57- - - - - - - - - -1
The school took and $70 on the second day by selling two adult tickets and four student tickets. It means that
2x + 4y = 70- - - - - - - - - -2
Subtracting equation 2 from equation 1, it becomes
- y = - 13
y = 13
Substituting y = 13 into equation 1, it becomes
2x + 3 × 13 = 57
2x + 39 = 57
2x = 57 - 39 = 18
x = 18/2
x = 9