问题
单项选择题
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 ？（）
A.$27.30
B.$51.00
C.$63.00
D.$70.00
E.$91.00
答案
参考答案：E
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。