单选题 A merchant sells an item at a 20 percent discount, but still makes a gross profit of 20 percent of the cost. What percent of the cost would the gross profit on the item have been if it had been sold without the discount?

【正确答案】 C
【答案解析】[解析] 设商品的成本价为a,不打折出售时该商人可以获得的毛利润为成本价的百分之x,则根据题意可得:
[80%×(1+x)]a=(1+20%)a
→x=50%