document.write( "Question 743397: 12 boys and 8 men can finish a piece of work in 5 days.and 8 boys nd 6men can finish it in 7 days . find the time by 1 man alone and 1 boy alone to finish the work.
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Algebra.Com's Answer #452862 by Edwin McCravy(20055) $\"\"$ $\"About$

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12 boys and 8 men can finish a piece of work in 5 days.and 8 boys nd 6men can finish it in 7 days . find the time by 1 man alone and 1 boy alone to finish the work.
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document.write( "Suppose 1 boy alone can can do 1 job in b days.\r\n" );
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document.write( "Then 1 boy's work rate is 1 job per b days or  or \r\n" );
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document.write( "Then 12 boys' work rate is 12 times  or \r\n" );
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document.write( "and 8 boys' work rate is 8 times  or \r\n" );
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document.write( "Suppose 1 man alone can can do 1 job in m days.\r\n" );
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document.write( "Then 1 man's work rate is 1 job per m days or  or \r\n" );
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document.write( "Then 8 men's work rate is 8 times  or \r\n" );
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document.write( "and 6 men's work rate is 6 times  or \r\n" );
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\n" ); document.write( ">>12 boys and 8 men can finish a piece of work in 5 days<<
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document.write( "So the combined work rate of 12 boys and 8 men is 1 job per 5 days or  or \r\n" );
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document.write( "So we get one equation from\r\n" );
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document.write( ">>8 boys and 6 men can finish it in 7 days<<\r\n" );
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document.write( "So the combined work rate of 8 boys and 6 men is 1 job per 7 days or  or \r
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document.write( "So we get the other equation from\r
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document.write( "So we have the system of equations\r
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document.write( "IMPORTANT:  DO NOT CLEAR OF FRACTIONS:\r
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document.write( "To eliminate the terms in m, multiply the first equation 
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document.write( "through by 3, and multiply the second equation through
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document.write( "by -4:\r
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document.write( "Adding those equations term by term gives\r
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document.write( "NOW we can clear of fractions.  Multiply both sides
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document.write( "by the LCD of 35b\r
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document.write( "So each boy will take 140 days.\r
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document.write( "Substitute 140 for b in\r
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document.write( "Multiply both sides by 10m\r
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document.write( "So each man will take 80 days.\r
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document.write( "Edwin

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