document.write( "Question 74234: I need help setting up this problem so I can solve it. Can anyone please help? \r
\n" ); document.write( "\n" ); document.write( "A motor boat can run 25 mph in still water. The boat starts at 7:00 am going upstream in a river whose current runs at 5 mph. How far up the river can the boat go and still be back at 12:00 noon? \r
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Algebra.Com's Answer #53237 by rmromero(383) $\"\"$ $\"About$

You can put this solution on YOUR website!


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document.write( "A motor boat can run 25 mph in still water. The boat starts at 7:00 am going upstream in a river whose current runs at 5 mph. How far up the river can the boat go and still be back at 12:00 noon? \r
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document.write( "What is asked in the problem?
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document.write( "    How far up the river can the boat go and still be back at 12:00noon?\r
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document.write( "Given:
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document.write( "Rate of motor boat in still water is 25mph
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document.write( "Rate of the current is 5mph
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document.write( "Time ranges from 7:00am to 12:00noon. That's is 5 hours difference.\r
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document.write( "Representation:
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document.write( "Let x be the distance the boat travel up or down
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document.write( "    y = the time it takes the boat to travel upstream
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document.write( "  5 - y = the time it takes the boat to travel downstream\r
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document.write( "                rate     *      time          =       distance
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document.write( "Upstream       25 - 5             y           =         x\r
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document.write( "Downstream     25 + 5           5 - y         =         x\r
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document.write( "                      (25 - 5)y = x      eq1
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document.write( "                  (25 + 5)(5-y) = x      eq2\r
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document.write( "Solve using substitution method\r
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document.write( "                   20y = x
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document.write( "                30( 5 - y) = x
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document.write( "                150 - 30y = 20y
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document.write( "                 150 = 50y
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document.write( "                   3h = y  this is the time it takes the boat to 
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document.write( "                           travel upstream\r
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document.write( "               5 - y = 5 - 3
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document.write( "                     = 2 hours --> this is the time it takes the boat to 
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document.write( "                                   travel downstream
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document.write( "   when y = 3\r
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document.write( "               20y = x
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document.write( "               20(3) = x
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document.write( "                 60m = x  This is the distance travel either upstream 
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document.write( "                          or downstream\r
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document.write( "                \n" );
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