document.write( "Question 81431: Shelia leaves on a long trip driving at a steady rate of 30mph. Her sister Allison leaves from the same location traveling to the same destination 2 hours later. She drives at a steady rate of 60mph. How long after Allison leaves home does she catch up to Shelia? \n" ); document.write( "

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Shelia leaves on a long trip driving at a steady rate of 30mph. Her sister Allison leaves from the same location traveling to the same destination 2 hours later. She drives at a steady rate of 60mph. How long after Allison leaves home does she catch up to Shelia?
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\n" ); document.write( "Let t = time on the road when A catches up with S
\n" ); document.write( "Then (t+2) = time S is on the road, when A catches up
\n" ); document.write( ":
\n" ); document.write( "We know that when A catches S, they will have traveled the same distance.
\n" ); document.write( "We can write a distance equation from that fact: Distance = speed * time
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\n" ); document.write( "A's dist = S's distance
\n" ); document.write( "60t = 30(t+2)
\n" ); document.write( "60t = 30t + 60
\n" ); document.write( "60t - 30t = 60
\n" ); document.write( "30t = 60
\n" ); document.write( "t = 60/30
\n" ); document.write( "t = 2 hrs for A to catch up with S
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\n" ); document.write( "Check our solution using the distance (S's time; 2 + 2 = 4 hrs)
\n" ); document.write( "30 * 4 = 120
\n" ); document.write( "60 * 2 = 120
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\n" ); document.write( "Did this make sense to you? Any question? \n" ); document.write( "

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