SOLUTION: Granville and preston are 642 miles apart. A car leaves preston bound for granville at 50mph. At the same time, another car leaves Granville bound for preston at 57mph. How long wi

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Question 988659: Granville and preston are 642 miles apart. A car leaves preston bound for granville at 50mph. At the same time, another car leaves Granville bound for preston at 57mph. How long will it take them to meet?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The easiest way to solve this is to
think of one car as standing still and
the other traveling at the sum of their speeds
( it doesn't matter which one is standing still )
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Let +t+ = time in hrs for them to meet
+642+=%28+50+%2B+57+%29%2At+
+642+=+107t+
+t+=+6+
It takes 6 hrs for them to meet
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check:
+d%5B1%5D+=+50t+
+d%5B1%5D+=+50%2A6+
+d%5B1%5D+=+300+ mi
and
+d%5B2%5D+=+57t+
+d%5B2%5D+=+57%2A6+
+d%5B2%5D+=+342+ mi
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+d%5B1%5D+%2B+d%5B2%5D+=+300+%2B+342+
+d%5B1%5D+%2B+d%5B2%5D+=+642+ mi
OK