单选题 A merchant purchased a jacket for $60 and then determined a selling price that equalled the purchase price of the jacket plus a markup that was 25 percent of the selling price. During a sale, the merchant discounted the selling price by 20 percent and sold the jacket. What was the merchant's gross profit on this sale?
(A) $0 (B) $3 (C) $4
(D) $12 (E) $15

【正确答案】 C

【答案解析】[解析] 设该商人所定的销售价格为x美元，则此价格为购买价格加上销售价格x的25%，根据题意可得到如下方程：
x=60+x·25%
→x=80美元，所以毛利润为：
80×(1-20%)-60=4美元