SOLUTION: Train A leaves the platform at 5 pm at a speed of 120 km/h and train B leaves the same platform on a parallel track in the same direction at 7 30 pm at 144 km/h. After how many hou

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Question 621378: Train A leaves the platform at 5 pm at a speed of 120 km/h and train B leaves the same platform on a parallel track in the same direction at 7 30 pm at 144 km/h. After how many hours will train B cross train A?
A)12.5
B)15
C)17.5
D)18
E)20
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

Train A leaves the platform at 5 pm at a speed of 120 km/h and train B leaves the same platform 

on a parallel track in the same direction at 7 30 pm at 144 km/h. 

After how many hourshighlight%28x%29 will train B cross train A?

 D = rt

 Distance = Distance

 144kmh%2Ax+=+120kmph%2A%28x%2B2.5hr%29

solving for x

  x = 120%2A2.5%2F24