document.write( "Question 432431: There are 200 heads on a farm and 540 feet.
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Algebra.Com's Answer #299818 by Edwin McCravy(20056) $\"\"$ $\"About$

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There are 200 heads on a farm and 540 feet.
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document.write( "Two ways to do it. In your head and by algebra.\r\n" );
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document.write( "In your head:\r\n" );
document.write( "540 feet means 270 pairs of feet, 200 of which are pairs of front feet,\r\n" );
document.write( "since all animals have 1 head and 1 pair of front feet.  The remaining 70\r\n" );
document.write( "pairs of feet are pairs of hind feet, which belong to the 70 cows, so the\r\n" );
document.write( "other 130 animals are chickens.\r\n" );
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document.write( "By algebra:\r\n" );
document.write( "x = number of cows\r\n" );
document.write( "y = number of chickens\r\n" );
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document.write( " x +  y = 200\r\n" );
document.write( "4x + 2y = 540\r\n" );
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document.write( "Multiply the top equation by -2\r\n" );
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document.write( "-2x - 2y = -400\r\n" );
document.write( " 4x + 2y = 540\r\n" );
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document.write( " 2x      = 140\r\n" );
document.write( "       x = 70  \r\n" );
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document.write( " x + y = 200\r\n" );
document.write( "70 + y = 200\r\n" );
document.write( "     y = 130.\r\n" );
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document.write( "Edwin

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