Answer: 35 adult tickets and 15 student tickets were sold.
Explanation:
Let x represent the number of adult tickets that were sold.
Let y represent the number of student tickets that were sold.
20 more adult tickets were sold and student tickets. It means that
x = y + 20
Adult tickets for the school play cost 6 dollars and student tickets cost 4 dollars. If $270 was collected, it means that
6x + 4y = 270- - - - - - - - - - - 1
Substituting x = y + 20 into equation 1, it becomes
6(y + 20) + 4y = 270
6y + 120 + 4y = 270
6y + 4y = 270 - 120
10y = 150
y = 150/10
y = 15
x = y + 20 = 15 + 20
x = 35