N1B7TNp13

Answer to Problem 13:

The first shop offers 60% off, the second 33% off, and the third 50% off.  Therefore, the first store has the best price per t-shirt, because it has the greatest discount.

Teacher Notes:

Some students will multiply by the original price by the different sale reductions.  Students should realize that since the price is constant, the best buy is obtained by the sale that has the greatest markdown.