document.write( "Question 819762: A library crew can shelve books in six hours. Another crew can do the job in four hours. If the first crew begins and is joined by the second crew one hour later, how many hours will it take for the job to be completed? \n" ); document.write( "

Algebra.Com's Answer #493237 by josmiceli(19441) $\"\"$ $\"About$

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Library crew's rate of working:
\n" ); document.write( " $\"+1%2F6+\"$
\n" ); document.write( "Fraction of the job done in 1 hour by library crew:
\n" ); document.write( " $\"+%28+1%2F6+%29%2A1+=+1%2F6+\"$
\n" ); document.write( "------------------
\n" ); document.write( " $\"+1+-+1%2F6+=+5%2F6+\"$ is the fraction left to be
\n" ); document.write( "finished by both crews
\n" ); document.write( "Let $\"+t+\"$ = time in hours to finish the job
\n" ); document.write( " $\"+1%2F6+%2B+1%2F4+=+%28%285%2F6%29%29+%2F+t+\"$
\n" ); document.write( " $\"+1%2F6+%2B+1%2F4+=+5%2F%286t%29+\"$
\n" ); document.write( "Multiply both sides by $\"+12t+\"$
\n" ); document.write( " $\"+2t+%2B+3t+=+10+\"$
\n" ); document.write( " $\"+5t+=+10+\"$
\n" ); document.write( " $\"+t+=+2+\"$ hrs
\n" ); document.write( "The job takes $\"+1+%2B+2+=+3+\"$ hrs to complete\r
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