document.write( "Question 1163733: One crew can seal a parking lot in 8 hours and another 12 hours. How long will it take to seal parking lot if the two crews work together? \n" ); document.write( "

Algebra.Com's Answer #787911 by Edwin McCravy(20054) $\"\"$ $\"About$

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Without algebra:\r\n" );
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document.write( "The LCM of 8 hours and 12 hours is 24 hours.\r\n" );
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\n" ); document.write( "One crew can seal a parking lot in 8 hours and another 12 hours.
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document.write( "So in 24 hours, the first crew can seal 3 parking lots.\r\n" );
document.write( "And in 24 hours, the second crew can seal 2 parking lots.\r\n" );
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document.write( "So together they can seal 5 parking lots in 24 hours.\r\n" );
document.write( "So together they can seal 1 parking lot in 24/5 = 4.8 hours.\r\n" );
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document.write( "With algebra.\r\n" );
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document.write( "Suppose it takes them x hours working together.\r\n" );
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document.write( "The first crew's rate is 1 parking lot per 8 hours or 1/8 parking lot per hour.\r\n" );
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document.write( "The second crew's rate is 1 parking lot per 12 hours or 1/12 parking lot per hour.\r\n" );
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document.write( "Then in x hours the first crew does (1/8)x of the sealing and the second\r\n" );
document.write( "crew does (1/12)x of the sealing.\r\n" );
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document.write( "Then their total is 1 driveway sealed:\r\n" );
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document.write( "(1/8)x + (1/12)x = 1 \r\n" );
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document.write( "     (1/8+1/12)x = 1\r\n" );
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document.write( "    (3/24+2/24)x = 1\r\n" );
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document.write( "         (5/24)x = 1\r\n" );
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document.write( "              5x = 24\r\n" );
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document.write( "               x = 24/5 = 4.8 hours.\r\n" );
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document.write( "Edwin

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