document.write( "Question 1154119: Mary can roof their house in 4 days working alone, her husband can roof their house in 6 days working alone. If they work together how long will it take to roof the house? \n" ); document.write( "

Algebra.Com's Answer #776477 by josmiceli(19441) $\"\"$ $\"About$

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$\"+1%2F4+\"$ is Mary's rate: [ 1 job ] / [ 4 days ]
\n" ); document.write( " $\"+1%2F6+\"$ is husband's rate: [ 1 job ] / [ 6 days ]
\n" ); document.write( "----------------------------------------------------
\n" ); document.write( " Let $\"+t+\"$ = time in days for job to get done
\n" ); document.write( "with them working together
\n" ); document.write( "Add their rates of working
\n" ); document.write( " $\"+1%2F4+%2B+1%2F6+=+1%2Ft+\"$
\n" ); document.write( "Multiply both sides by $\"+12t+\"$
\n" ); document.write( " $\"+3t+%2B+2t+=+12+\"$
\n" ); document.write( " $\"+5t+=+12+\"$
\n" ); document.write( " $\"+t+=+2.4+\"$ days
\n" ); document.write( "They get it done in 2.4 days
\n" ); document.write( "--------------------------------
\n" ); document.write( "check:
\n" ); document.write( " $\"+.25+%2B+.1667+=+1%2F2.4+\"$
\n" ); document.write( " $\"+.41667+=+.41667+\"$
\n" ); document.write( "OK
\n" ); document.write( " \n" ); document.write( "

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