Anne is a bargain-minded shopper. Normally, her favorite toothpaste costs the same at both of her local supermarkets, but the stores are having competing sales this week. At one store, there is a bonus offer: buy 2, get 1 free. At the other store, toothpaste is being sold at 40 percent off. Anne instantly opts for the first offer. Was that really the less-expensive choice? (Hint: Is “buy 2, get 1 free” the same as 50 percent off?)