document.write( "Question 1205975: Josh can clean the math building on his campus in 3 hours. Ken takes 7 hours to clean the same building. If they work​ together, how long will it take them to clean this​ building?\r
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Algebra.Com's Answer #843100 by mananth(16946)\"\" \"About 
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Josh can clean the math building on his campus in 3 hours. Ken takes 7 hours to clean the same building. If they work​ together, how long will it take them to clean this​ building?\r
\n" ); document.write( "\n" ); document.write( "Josh can clean the math building on his campus in 3 hours\r
\n" ); document.write( "\n" ); document.write( "Assune cleaning the building as one job,\r
\n" ); document.write( "\n" ); document.write( "So josh can do 1/3 of the job in 1 hour.\r
\n" ); document.write( "\n" ); document.write( "Ken takes 7 hours to clean the same building.\r
\n" ); document.write( "\n" ); document.write( "So he does 1/7th of the job in 1 hour\r
\n" ); document.write( "\n" ); document.write( "If they work together they do (1/3 +1/7 ) of the job in 1 hour\r
\n" ); document.write( "\n" ); document.write( "= 10/21 of the job in 1 hour\r
\n" ); document.write( "\n" ); document.write( "Therefore to complete the job together they take 21/10 hours = 2.1 hours.\r
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