Your school sells tickets for its winter concert. Student tickets are $5 and adult tickets are $10. If your school sells 85 tickets and makes $600, how many of each ticket did they sell?

Let s be the number of student tickets and a be the number of adult tickets.

s + a = 85; a = 85 - s

Also,

5s + 10a = 600

Substituting a from the first equation

5s + 10 (85 - s) = 600

-5s = - 250

s = 50

a = 85 - 50 = 35

The school sold 50 student tickets and 35 adult tickets.