Answer:
60 student tickets and 40 adult tickets were sold
Explanation:
Let s represent student tickets and a adult tickets, then the system of equations can be written as
s - a = 20 →(1)
2s + 4a = 280 → (2)
Multiply (1) by 4 and add to (2) to eliminate a
4s - 4a = 80 → (3)
Add (2) and (3) term by term
6s = 360 ( divide both sides by 6 )
s = 60
Substitute s = 60 into (1)
60 - a = 20 ( subtract 60 from both sides )
- a = - 40 ( multiply both sides by - 1 )
a = 40
Thus
60 student and 40 adult tickets were sold.