Q26
Running at their respective constant rates, machine X takes 2 days longer to produce W widgets than machine Y. At these rate, if the two machines together produce 5/4 W widgets in 3 days, how many days would it take machine X alone to produce 2W widgets?
A.4
B.6
C.8
D.10
E.12
答案是E, 可是我算了半天都是C。 谁能告诉我答案是怎么算出来的,谢谢!
(5/4)/(1/x+1/(x+2))=3==>x=6,x=5/4
2/(1/6)=12
设Xmachine X天完成,Ymachine X+2天完成,效率分别是1/x,1/x+2
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