### Home > A2C > Chapter 9 > Lesson 9.2.3 > Problem 9-109

9-109.

Create a system of equations and solve.

Where *a* = number of adult tickets sold and *c* = number of children's tickets sold:

8.5*a* + 5*c* = 5000*a* + *c* = 685

They would need to sell at least 450 adult tickets.