EXPLANATION
Let's see the facts:
Discount= 15%
Shirt price = 20% off from original = 80%*original price = 0.8*original price
Amount paid = $14.96 [No tax]
Let's call x to the original price of the shirt, the equation would be as follows:
14.96 = (1-0.15)*(1-0.2)*x [Subtracting numbers]
14.96 = 0.85*0.8*x [Multiplying like numbers]
14.96 = 0.68x [Dividing both numbers by 0.68]
14.96/0.68 = x [Simplifying