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July 29, 2014

July 29, 2014

Posted by **Debbie** on Thursday, February 14, 2008 at 8:13pm.

- Math -
**Christiaan**, Thursday, February 14, 2008 at 8:49pmIf we take the speed of the freight train to be x, and the speed of the passenger train to be y, we get that:

1)y=x+12

2)270/y=210/x

So if we replace y in the second equation by the y we found in the forst equation, we get that:

270/(x+12)=210/x

=>210*(x+12)=270x

=>60x=2520

=>x=42

=>y=54

So the freight train moves at 42mph and the passenger train moves at 54mph

- Math -
**Reiny**, Thursday, February 14, 2008 at 8:51pmLet the speed of the freight train be x mph

then the speed of the passenger train is x+12 mph

Time for freight train = 210/x

time for passenger train = 270/(x+12)

but they are equal so....

270/(x+12) = 210/x

cross-multiply and solve.

Let me know what you got.

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