document.write( "Question 25642: Mary, Sue and Bill work at a motel. Working alone, it takes Mary 10 hours, Sue 8 hours, and Bill 12 hours to clean the whole motel. One day Mary came to work 2 hours early and cleaned until Bill and Sue arrived. How long did it take them to finish the job working together? \n" ); document.write( "
Algebra.Com's Answer #13757 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
Work done = (rate)(time)
\n" ); document.write( "Mary work along: =(1/10 job/hr.)(2 hrs.)=1/5 job
\n" ); document.write( "Now let the time \"they\" work together be \"x\".
\n" ); document.write( "Note the phrase \"...take them to finish...\" can
\n" ); document.write( "have two meanings.
\n" ); document.write( "It can mean Bill and Sue finished the job, or
\n" ); document.write( "it can mean Mary, Bill, and Sue finished the job.
\n" ); document.write( "If the 1st you get the following equation:
\n" ); document.write( "(1/8)x+(1/12)x=4/5
\n" ); document.write( "15x+10x=96
\n" ); document.write( " 27x=96
\n" ); document.write( " x=96/27 hrs. (time Bill and Sue work together to finish the job)
\n" ); document.write( "If all three work together for \"x\" hours:
\n" ); document.write( " (1/8)x+(1/12)x+(1/10)x=4/5
\n" ); document.write( " 15x+10x+12x=96
\n" ); document.write( " 37x=96
\n" ); document.write( " x=96/37 hrs (time Bill and Sue and Mary work together)\r
\n" ); document.write( "\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );