System of Equations (Help! Urgent!)

Question

I came across this question but I could not figure it out. Could you please help me and explain how to find the answer? Thanks!

Brenda's school is selling tickets to a spring musical. On the first day of ticket sales the school sold 3 adult tickets and 9 child tickets for a total of $75. The school earned $67 on the second day by selling 8 adult tickets and 5 child tickets. What is the price of one adult ticket and one child ticket?

Write and solve a system of equations to figure out the price of a child ticket and an adult ticket. Define your variables.

Variables: 

Equations:

Solve by Substitution or Elimination:

Answer 1

x prize for adult and y for child:

3x + 9y = 75 I ·5

8x + 5y = 67 I·(-9)

By adding we get:

15x - 72x = 375 - 603;

-57x = - 228; x = 4

9y = 75 - 12; 9y = 63, y = 7