document.write( "Question 347351: John by himself can paint 4 rooms in 10 hrs. if he hires Mark to help, they can do the same job together in 6 hrs. if he lets Mark work alone, how long will it take for Mark to paint 4 rooms? \n" ); document.write( "
Algebra.Com's Answer #248370 by stanbon(75887)\"\" \"About 
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John by himself can paint 4 rooms in 10 hrs. if he hires Mark to help, they can do the same job together in 6 hrs. if he lets Mark work alone, how long will it take for Mark to paint 4 rooms?
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\n" ); document.write( "John DATA:
\n" ); document.write( "time = 10 hrs/job ; rate = 1/10 job/hr
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\n" ); document.write( "Together DATA:
\n" ); document.write( "time = 6 hrs/job ; rate = 1/6 job/hr
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\n" ); document.write( "Mark DATA:
\n" ); document.write( "time = x hrs/job ; rte = 1/x job/hr.
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\n" ); document.write( "Equation:
\n" ); document.write( "rate + rate = together rate
\n" ); document.write( "1/10 + 1/x = 1/6
\n" ); document.write( "Multiply thru by 30x to get:
\n" ); document.write( "3x + 30 = 5x
\n" ); document.write( "2x = 30
\n" ); document.write( "x = 15 hrs (time for Mark to do the job alone)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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