document.write( "Question 1148317: Joan takes 7 hours to clean the basement. It takes mike 12 hours to do this job. How long would it take if they worked together? \n" ); document.write( "

Algebra.Com's Answer #769691 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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Joan takes 7 hours to clean the basement.
\n" ); document.write( " It takes Mike 12 hours to do this job.
\n" ); document.write( " How long would it take if they worked together?
\n" ); document.write( "\:
\n" ); document.write( "Let t = time required working together
\n" ); document.write( "let the completed job = 1
\n" ); document.write( "Each will do a fraction of the job, the two fractions add up to 1 (completed job)
\n" ); document.write( " $\"t%2F7\"$ + $\"t%2F12\"$ = 1
\n" ); document.write( "Get rid of the fractions, multiply by 84
\n" ); document.write( "84* $\"t%2F7\"$ + 84* $\"t%2F12\"$ = 84(1)
\n" ); document.write( "Cancel the denominators
\n" ); document.write( "12t + 7t = 84
\n" ); document.write( "19t = 84
\n" ); document.write( "t = 84/19
\n" ); document.write( "t = 4.421 hrs, or 4 + .421(60) ~ 4 hrs 25 min
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