document.write( "Question 1192916: When a plane flies with the wind, it can travel 1680 miles in 4 hours. When the plane flies in the opposite direction, against the wind, it takes 5 hours to fly the same distance. Find the rate of the plane in still air and the rate of the wind.\r
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\n" ); document.write( "\n" ); document.write( "The rate of the wind is ____ miles per hour. \n" ); document.write( "

Algebra.Com's Answer #824848 by Edwin McCravy(20055) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "Make this chart. Let r = rate in still air, and\r\n" );
document.write( "let w = the rate of the wind.\r\n" );
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document.write( "              | Rate | Time | Distance\r\n" );
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document.write( "With the wind | r+w  |   4  |  1680\r\n" );
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document.write( "Against wind  | r-w  |   5  |  1680 \r\n" );
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document.write( "               Rate  x Time = Distance \r\n" );
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document.write( "                   (r+w)(4) = 1680 \r\n" );
document.write( "                   (r-w)(5) = 1680\r\n" );
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document.write( "                Divide the first through by 4 and the\r\n" );
document.write( "                second through by 5:\r\n" );
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document.write( "Add those two equations term by term, and the w's will cancel\r\n" );
document.write( "and you can find r.  Then substitute to find w.\r\n" );
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document.write( "Edwin

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