document.write( "Question 201114: Two trains leave at the same point. One train leaves at noon at 50mph. The other train leaves 2 hours later at 90mph. At what time will the second train catch the first train? \n" ); document.write( "

Algebra.Com's Answer #151329 by josmiceli(19441) $\"\"$ $\"About$

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Assume I have a stopwatch. I'll start
\n" ); document.write( "it when the 2nd train leaves at 2 PM.
\n" ); document.write( "How far has the 1st train gone in
\n" ); document.write( "2 hours?
\n" ); document.write( " $\"50%2A2+=+100\"$ miles
\n" ); document.write( "When I start the stopwatch, both trains
\n" ); document.write( "will travel for $\"t\"$ hrs
\n" ); document.write( "If the 2nd train's distance is $\"d\"$ ,
\n" ); document.write( "the 1st train's distance is $\"d+-+100\"$
\n" ); document.write( "Now I can write an equation for each one
\n" ); document.write( "2nd train:
\n" ); document.write( " $\"d+=+90t\"$
\n" ); document.write( "1st train:
\n" ); document.write( " $\"d+-+100+=+50t\"$
\n" ); document.write( "Substituting:
\n" ); document.write( " $\"90t+-+100+=+50t\"$
\n" ); document.write( " $\"40t+=+100\"$
\n" ); document.write( " $\"t+=+2.5\"$
\n" ); document.write( "This is the elapsed time starting at 2 PM
\n" ); document.write( "The 2nd train catches the 1st train at 4:30 PM
\n" ); document.write( " \n" ); document.write( "

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