document.write( "Question 104703: Train A leaves a station traveling at 80 kilometers per hour. 8 hours later, train B leaves the same staion traveling in the same direction at 90 kilometers per hour. How long does it take train B to catch up to train A? \n" ); document.write( "

Algebra.Com's Answer #76288 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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Train A leaves a station traveling at 80 kilometers per hour. 8 hours later, train B leaves the same station traveling in the same direction at 90 kilometers per hour. How long does it take train B to catch up to train A?
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\n" ); document.write( "One thing to notice about these \"catch-up\" problems, is that when one catches
\n" ); document.write( "up with the other, they will have traveled the same distance, we don't what the
\n" ); document.write( "distance is, but we do know that they are the same. We can make a distance
\n" ); document.write( " equation from this simple fact.
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\n" ); document.write( "Let t = time required by Train B to catch up
\n" ); document.write( "then
\n" ); document.write( "(t+8) = time when Train A is caught
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\n" ); document.write( "Distance = speed * time:
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\n" ); document.write( "90t = 80(t+8)
\n" ); document.write( "90t = 80t + 640
\n" ); document.write( "90t - 80t = 640
\n" ); document.write( "10t = 640
\n" ); document.write( "t = 640/10
\n" ); document.write( "t = 64 hr for B to catch up with A
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\n" ); document.write( "Now, we can find out the distances, and by them being equal, we know that our
\n" ); document.write( "solutions are correct: Train A time: 64+8 = 72
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\n" ); document.write( "A: 80 * 72 = 5760 mi
\n" ); document.write( "B: 90 * 64 = 5760 also
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\n" ); document.write( "Did this make sense to you? Any questions? \n" ); document.write( "

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