一道菜题，可是我还是不会

samgxs

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, haw many calculators were in the shipment?

A24 b25 c26 d28 e30

－－根本看不懂啊－－

tongxun

我已经在你这个帖子的上面解释了。这种情况，难免。

tongxun

请看：题干：a shipment of x identical calculators
问题：$5 more than the average (arithmetic mean) cost of the x calculators。
因此，可以肯定地说indicate that the cost is only the shipment

samgxs

我今天做题真的这样想。。。。。。。。。

猫猫头

哎，你不要钻牛角尖好不好
题目就是这个意思

samgxs

“$5 more than the average (arithmetic mean) cost of the x calculators”this sentence does not indicate that the cost is only the shipment.....

tongxun

right.(5+ 300/x)(x-2)=120+300

猫猫头

(300/x+5)(x-2)-300=120
x=30