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 #843107 by math_tutor2020(3817)\"\" \"About 
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\n" ); document.write( "Consider the area to clean is 210 square feet.
\n" ); document.write( "I'm getting this value from the fact 7*3 = 21 is the LCM of the given values.
\n" ); document.write( "Then I tacked on a 0 at the end to make the square footage more realistic.
\n" ); document.write( "This is just an example value. Feel free to pick another.\r
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\n" ); document.write( "\n" ); document.write( "Josh cleans 210 sq ft in 3 hours when working alone.
\n" ); document.write( "His unit rate is 210/3 = 70 sq ft per hour.\r
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\n" ); document.write( "\n" ); document.write( "Ken cleans 210 sq ft in 7 hours when working alone.
\n" ); document.write( "His unit rate is 210/7 = 30 sq ft per hour.\r
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\n" ); document.write( "\n" ); document.write( "Add the unit rates: 70+30 = 100
\n" ); document.write( "If the two men work together, without either person getting in the way of the other, then their combined unit rate is 100 sq ft per hour.\r
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\n" ); document.write( "\n" ); document.write( "When working together it will take 210/100 = 2.1 hours.\r
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\n" ); document.write( "\n" ); document.write( "If you wanted the answer in minutes only, then,
\n" ); document.write( "2.1 hrs = 2.1*60
\n" ); document.write( "2.1 hrs = 126 min\r
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\n" ); document.write( "\n" ); document.write( "Or if you wanted hrs+min format,
\n" ); document.write( "126 min = 120 min + 6 min
\n" ); document.write( "126 min = 2 hr + 6 min
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