问题
单项选择题
A merchant paid $300 for a shipment of x identical calculators. The merchant used 2 of the calculators as demonstrators and sold each of the others for $5 more than the average (arithmetic mean) cost of the X calculators. If the total revenue from the sale of the calculators was $120 more than the cost of the shipment, how many calculators were in the shipment ？（）
A．24
B．25
C．26
D．28
E．30
答案
参考答案：E
解析：
根据题意可得到如下方程：
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