Question 851234
The number of shirts is irrelevant to the equation.
x - .80x = 30 (subtracting 80% rather than 20% because the retail price less the discount = 80%)
Subtract
.20x = 30
Divide each side by .20
x = 150
.
Let's work it backward to make certain.
If the shirts cost 150 retail and have a discount of 20%,
150 * .20 = $30.00
Success!