document.write( "Question 603368: Joe can do a job twice as fast as Sam. Together they can do the job in 20 minutes. How long does it take Joe working alone to do the job? \n" ); document.write( "
Algebra.Com's Answer #380679 by AnlytcPhil(1807)\"\" \"About 
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Joe can do a job twice as fast as Sam.
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document.write( "Let Sam's rate in jobs per hour be S.\r\n" );
document.write( "Then Joe's rate in jobs per hour is 2S.\r\n" );
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\n" ); document.write( "Together they can do the job in 20 minutes.
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document.write( "Their combined rate is 1 job per 20 minutes = 1 job per 1/3 hour or 3 jobs per hour.\r\n" );
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document.write( "So the sum of their rates is 3 jobs per hour\r\n" );
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document.write( "S + 2S = 3\r\n" );
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document.write( "    3S = 3\r\n" );
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document.write( "     S = 1\r\n" );
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document.write( "So Sam's rate is S = 1 job per hour, so it'll Sam 1 hour to do 1 job \r\n" );
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document.write( "and Joe's rate is 2S = 2·1 = 2 jobs per hour, so it'll take Joe half\r\n" );
document.write( "an hour (or 30 minutes) to do 1 job.\r\n" );
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document.write( "Edwin
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