Answer:
The discount rate operated by the coupon is 20%.
Step-by-step explanation:
Since the pair of shoes normally sells for $ 90, but through the application of a discount coupon it sells for $ 72, to determine the discount percentage made by this coupon it is necessary to perform the following calculation:
90 = 100
72 = X
(72 x 100) / 90 = X
7,200 = 90 = X
80 = X
100 - 80 = 20
Thus, the discount operated by the coupon is 20%.