SOLUTION: Two trains, one express and one local, leave Indianapolis at noon and head for Chicago 220 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of t

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Question 673883: Two trains, one express and one local, leave Indianapolis at noon and head for Chicago 220 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of the local. Find the speed of each train
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the speed of the local train
Let +t+ = the travel time for the local train
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Equation for local train:
(1) +220+=+s%2At+
Equation for express train:
(2) +220+=+2s%2A%28+t+-+2+%29+
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(2) +220+=+2%2As%2At+-+4s+
Substitute (1) into (2)
(2) +220+=+2%2A220+-+4s+
(2) +4s+=+440+-+220+
(2) +4s+=+220+
(2) +s+=+55+
+2s+=+110+
The express train's speed is 110 m,i/hr
The local train's speed is 55 mi/hr
check answer:
(1) +220+=+s%2At+
(1) +t+=+220%2F55+
(1) +t+=+4+
and
(2) +220+=+2s%2A%28+4+-+2+%29+
(2) +220+=+4s+
(2) +s+=+55+
OK