单选题 A retailer sold an appliance for 30 percent above cost, which represented a gross profit of $21.00. For what price did the retailer sell the appliance?
【正确答案】 E
【答案解析】[解析] 设这件器具的成本为x美元，则根据题意可得：
30%x=21→x=70美元
所以这件器具的出售价格为70(1+30%)=91美元。