document.write( "Question 1030876: Renee rows a boat downstream for 27 miles. The return trip upstream took 24 hours longer. If the current flows at 4 mph, how fast does Renee row in still water? \n" ); document.write( "

Algebra.Com's Answer #645660 by ikleyn(52781) $\"\"$ $\"About$

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\n" ); document.write( "Renee rows a boat downstream for 27 miles. The return trip upstream took 24 hours longer.
\n" ); document.write( "If the current flows at 4 mph, how fast does Renee row in still water?
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document.write( "Let \"u\" be Renee's boat speed in still water, in mph.\r\n" );
document.write( "Then the effective speed downstream is  (u + 4)  mph  (the speed relative to the river's bank).\r\n" );
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document.write( "The effective speed upstream is  (u - 4)  mph  (the speed relative to the river's bank).\r\n" );
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document.write( "The time spent moving downstream is   hours.\r\n" );
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document.write( "The time spent moving   upstream is   hours.\r\n" );
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document.write( "The condition says that\r\n" );
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document.write( " -  = 24.\r\n" );
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document.write( "To solve this equation, multiply both sides by (u-4)*(u+4). You will get\r\n" );
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document.write( "27*(u+4) - 27*(u-4) = 24*(u-4)*(u+4).\r\n" );
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document.write( "Simplify\r\n" );
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document.write( " = ,\r\n" );
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document.write( " = ,\r\n" );
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document.write( " = ,\r\n" );
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document.write( " = ,\r\n" );
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document.write( " =  = ,\r\n" );
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document.write( "u =  = 5 mph.\r\n" );
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document.write( "Answer. Renee's boat speed in still water is  5  mph.\r\n" );
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document.write( "Check.  Time downstream  =  3 h.  Time upstream    = 27 h.  Time difference 27 h - 3 h = 24 h.\r\n" );
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