一道英语智力题John,Heather,andBarbaraarewaitingatthetrainstation.Eachofthethreeiswaitingforadifferenttrain.Whentheycheckthestationclock,theyrealisethatHeatherisgoingtohavetowaittwiceaslongforhertrainasJohn

Question

一道英语智力题
John,Heather,and Barbara are waiting at the train station.Each of the three is waiting for a different train.When they check the station clock,they realise that Heather is going to have to wait twice as long for her train as John,while Barbara will have to wait twice as long as Heather.What time is it now?
Destination:Newburgh Springfield Clarksville
Track:3 7 4
Departure:4:48 4:57 5:15
现在我知道答案是4：39,但是不知道为什么,

Answer 1

把这三个人用ABC来代替
A等的时间是X,B等的时间就是2X,C是4X
2X-X=4：57-4：48
解题,X=0：09
现在的时间是4：48-0：09=4：39
这道题有没有C实际是无所谓的,多余的一个条件