document.write( "Question 147179: Trainsa a and b are traveling in the same direction on parallel tracks. Train a is traveling at 60mph and train b is traveling at 70mph. train a passes the station at 12:10p.m. If train b passes the same station at 12:22p.m., at what time will train b catch up to train a. \n" ); document.write( "

Algebra.Com's Answer #107525 by josmiceli(19441) $\"\"$ $\"About$

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Assume I have a stopwatch and I'm on train b
\n" ); document.write( "I'm in contact by cellphone with the station
\n" ); document.write( "They tell me that train a went by at 12:10.
\n" ); document.write( "Then I pass the station at 12:22, and I start my stopwatch
\n" ); document.write( " $\"12\"$ minutes went by, or $\"12%2F60\"$ hr
\n" ); document.write( "I know that train a travels at 60 mi/hr
\n" ); document.write( " $\"d+=+r%2At\"$
\n" ); document.write( " $\"d+=+60%2A%2812%2F60%29\"$
\n" ); document.write( " $\"d+=+12\"$ mi
\n" ); document.write( "That's how far train a has gone ahead of me
\n" ); document.write( "I'm going to press the stopwatch again when the trains meet.
\n" ); document.write( "Let $\"d\"$ = the distance I (train b) will have gone in that time
\n" ); document.write( "Then $\"d+-+12\"$ will be the distance that train a has gone.
\n" ); document.write( "I can write
\n" ); document.write( " $\"d+-+12+=+60t\"$
\n" ); document.write( " $\"d+=+70t\"$
\n" ); document.write( "Substitute the 2nd equation in the 1st
\n" ); document.write( " $\"70t+-+12+=+60t\"$
\n" ); document.write( " $\"10t+=+12\"$
\n" ); document.write( " $\"t+=+1.2\"$ hr
\n" ); document.write( "or 1 hr 12 min
\n" ); document.write( "This is 1 hr 12 min past 12:22 when I started the stopwatch, or
\n" ); document.write( "13:34, which is 1:34 PM\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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