Matthew M. answered • 04/29/19

Experienced Math Tutor and Graduate of Boston College

Let's say s is the price of one shirt. Since we have 3 shirts, we have 3s.

Our coupon for 10 dollars off means we can take 10 off the price of the 3 shirts: 3s-10.

Since 65 is the total amount we spent, 3s-10=65

Hope this helps!