document.write( "Question 562467: Mary can paint a house in 4 hours. John can paint a house in 6 hours. How long will it take for them to paint a house together \n" ); document.write( "

Algebra.Com's Answer #364581 by Edwin McCravy(20060) $\"\"$ $\"About$

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Mary can paint a house in 4 hours. John can paint a house in 6 hours. How long will it take for them to paint a house together
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document.write( "Make this chart:\r\n" );
document.write( "                       number of       number of        rate\r\n" );
document.write( "                        houses           hours           in\r\n" );
document.write( "                        painted         required     houses/hour\r\n" );
document.write( "Mary painting alone      \r\n" );
document.write( "John painting alone\r\n" );
document.write( "Both painting together \r\n" );
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document.write( "Let x = the number of hours it will take both painting together.\r\n" );
document.write( "Fill that in and the number of hours required for Mary and John, 4 and\r\n" );
document.write( "6 respectively.\r\n" );
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document.write( "                       number of       number of        rate\r\n" );
document.write( "                        houses           hours           in\r\n" );
document.write( "                        painted         required     houses/hour\r\n" );
document.write( "Mary painting alone                        4 \r\n" );
document.write( "John painting alone                        6\r\n" );
document.write( "Both painting together                     x\r\n" );
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document.write( "In each case 1 house is painted. We fill in 1 for the number of houses\r\n" );
document.write( "painted in each case:\r\n" );
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document.write( "                       number of       number of        rate\r\n" );
document.write( "                        houses           hours           in\r\n" );
document.write( "                        painted         required     houses/hour\r\n" );
document.write( "Mary painting alone        1               4\r\n" );
document.write( "John painting alone        1               6\r\n" );
document.write( "Both painting together     1               x\r\n" );
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document.write( "Fill in the rates in houses/hour bu dividing the number of houses\r\n" );
document.write( "by the number of hours required.\r\n" );
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document.write( "                       number of       number of        rate\r\n" );
document.write( "                        houses           hours           in\r\n" );
document.write( "                        painted         required     houses/hour\r\n" );
document.write( "Mary painting alone        1               4             1/4 \r\n" );
document.write( "John painting alone        1               6             1/6\r\n" );
document.write( "Both painting together     1               x             1/x\r\n" );
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document.write( "The equation comes from:\r\n" );
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document.write( "                    +  =    \r\n" );
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document.write( "                        +  = \r\n" );
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document.write( "Solve that and get x = 2.4 hours or 2 hours 24 minutes\r\n" );
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document.write( "Edwin

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