Let the number of adult tickets be x.
Since there are 110 tickets sold in all, student tickets will be 110 - x.
Cost for adult tickets = 7*x = 7x
Cost for student tickets = 4*(110 -x) = 4*110 - 4*x = 440 - 4x
Total cost = $569
7x + (440 - 4x) = 569
7x + 440 - 4x = 569
7x - 4x = 569 - 440
3x = 129
x = 129/3
x = 43
Recall x is the number of adults tickets = 43
Student tickets = (110 - x) = 110 - 43 = 67
Therefore from the number of tickets sold it is safe to assume that 43 adults and 67 students attended the play.
