GWD 5-17

[tomato1224]

Company S produces two kinds of stereos: basic and deluxe. Of the stereos produces by Company S last month, 2/3 were deluxe. If it takes 7/5 as many hours to produce a deluxe stereo as it does to produce a basic stereo, then the number of hours to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

Ans: A

我選E
不知道該如何算出
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