GWD-8-28

linmeimei

Q28:
A car traveling at a certain constant speed takes 2 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 75 kilometers per hour.  At what speed, in kilometers per hour, is the car traveling?

A.    71.5
B.    72
C.    72.5
D.    73
E.    73.5
Answer: B

为什么我算不出正确答案。。。

jiuwang

1/x-2/3600=1/75   算出来是72