A total of 516 tickets were sold for the school day. There were either adult tickets or student tickets. The number of student tickets sold was three times the number of adult tickets were sold?

x: number of adult tickets

y: number of student tickets

A total of 516 tickets were sold for the school day

x + y = 516

The number of student tickets sold was three times the number of adult tickets.

y = 3*x

Substitute y in the first equation with 3*x

x + 3*x = 516

4*x = 516

x = 129 adult tickets

Now solve for y

y = 3*129 = 387 student tickets