document.write( "Question 889110: A father can wash a car in 20 min and his son can wash a car in 5 min. If they togather start to wash a car how much time will be required? \n" ); document.write( "

Algebra.Com's Answer #537891 by Edwin McCravy(20056) $\"\"$ $\"About$

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A father can wash a car in 20 min and his son can wash a car in 5 min. If they togather start to wash a car how much time will be required?
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document.write( "What??  The father takes 4 times as long as his son?  I don't believe anybody\r\n" );
document.write( "can wash a car, and do a good job, in 5 minutes.  This problem is either\r\n" );
document.write( "botched or very unrealistic.  However I'll do it anyway:\r\n" );
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document.write( "The father's washing rate in cars per minute is 1 car per 20 minutes or\r\n" );
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document.write( "The son's very speedy washing rate in cars per minute is 1 car per 5 minutes\r\n" );
document.write( "or\r\n" );
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document.write( "Suppose the answer is x minutes.\r\n" );
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document.write( "Then their combined washing rate in cars per minute is 1 car per x minutes or\r\n" );
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document.write( "The equation comes from \r\n" );
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document.write( "Multiply through by LCD = 20x and solve.  The answer is \r\n" );
document.write( "x = 4 minutes.\r\n" );
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document.write( "Edwin

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