Answer:
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
