Peter buys tickets for his family to see his favorite movie, Elephant Mistake. He pays
$37.50 for 2 adult tickets and 2 student tickets. The next week he goes back with
his friends and pays $35.25 for 1 adult ticket and 3 student tickets. Choose the
system of equations that can be solved to find the price of an adult ticket, a, and
the price of a student ticket, y.