Toby considers buying three different pairs of running shoes: a $20.00 pair, a $40.00 pair, and
a $60.00 pair. He has three coupons: one for 10% off one item, one for 20% off one item, and
one for 25% off one item. Assume that Toby buys at least one pair of running shoes and uses
a coupon for each pair of shoes he buys. How to do it
