Question 116729
An express train travels 90 kilometers per hour from smallville to megatown. A local train takes 2.5 hours longer to travel then same distance at 50 kilometers per hour. how far apart are Smallville and Megatown.
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Let d = distance from S to M
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Write a time equation, Time = Distance/speed:
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Local train time - Express train time = 2.5 hrs
{{{d/50}}} - {{{d/90}}} = 2.5
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Multiply equation by 450 to get rid of the denominators
450*{{{d/50}}} - 450*{{{d/90}}} = 450(2.5)
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Cancel the denominators, we have:
9d - 5d = 1125
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4d = 1125
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d = 1125/4
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d = 281.25 km from S to M
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Check solution by finding the times for each train:
Local: 281.25/50 = 5.625 hrs
Exprs: 281.25/90 = 3.125 hrs
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Time difference is: 2.5 hrs; confirms our solution
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Did this make sense to you? Any questions?

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