Tickets to a show cost $10 in advance and $15 at the door. If 120 tickets are sold for a total of $1,390, how many of the tickets were bought in advance?

Let x = number of tickets bought in advance       y = number of tickets bought at the door We have two unknowns therefore we need to equations to solve the problem. We do as follows: x + y = 120 10x + 15y = 1390 SOlving simultaneously, x = 82 y = 38