Atotal of
572
tickets were sold for the school play. they were either adult tickets or student tickets. the number of student tickets sold was three times the number of adult tickets sold. how many adult tickets were sold?

Using x as the number of adult tickets sold
If 3x as many student tickets were sold as adults 
--> the number of student tickets is 3x

If the total tickets is 572 and made up of 3x and x

This equation represents the relation ship
Total = 572
number of adult tickets + number of student tickets = 572
x + 3x = 572

When solving for x, we will find the number of adult tickets
x+3x =572
4x=572
x= 572/4
x= 143

143 adult tickets were sold

A. is the answer in this question