Q26:

Running at their respective constant rates, machine X takes 2 days longer to produce w widgets than machine Y.  At these rates, 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.      12Answer: E How to calculate?

Answer: E How to calculate?

设X用X天完成W，则Y需要X－2天。 (1/x+1/(x-2))*3=5/4,求得X＝6。
完成2W的时间则为12