document.write( "Question 1114406:
\n" ); document.write( "A child is running on a moving sidewalk in an airport. When he runs against the sidewalk's motion, he travels 32ftin 8 seconds. When he runs with the sidewalk's motion, he travels 120ftin 12 seconds. What is the rate of the child on a still sidewalk and what is the rate of the moving sidewalk? \n" ); document.write( "

Algebra.Com's Answer #729343 by ikleyn(52864) $\"\"$ $\"About$

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document.write( "Let u be the child's own speed in ft/s, and\r\n" );
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document.write( "let v be the moving sidewalk speed.\r\n" );
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document.write( "The child's effective velocity running with he sidewalk's motion is \r\n" );
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document.write( "u + v = 120/12 = 10  ft/s\r\n" );
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document.write( "The child's effective velocity running against he sidewalk's motion is \r\n" );
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document.write( "u - v = 32/8 = 4  ft/s\r\n" );
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document.write( "Again\r\n" );
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document.write( "u + v = 10\r\n" );
document.write( "u - v =  4\r\n" );
document.write( "-------------------------Add the equations to exclude v\r\n" );
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document.write( "2u = 10 + 4 = 14   ====>  u = 7 ft/s.\r\n" );
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document.write( "Then v = 10-u = 10-7 = 3 ft/s.\r\n" );
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document.write( "Answer.  The child own speed is 7 ft/s.  The running sidewalk speed  is 3 ft/s.\r\n" );
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