document.write( "Question 1162087: The current in a stream moves at a rate of 4 mph. If a boat travels 56 miles downstream in the same time that it takes to travel 28 miles upstream, what is the speed of the boat in still water? \n" ); document.write( "

Algebra.Com's Answer #785807 by ikleyn(52782) $\"\"$ $\"About$

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document.write( "From the condition, you have this equation\r\n" );
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document.write( " = ,\r\n" );
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document.write( "where U is the speed of the boat in still water.\r\n" );
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document.write( "Notice that each side of the equation is the corresponding traveled time.\r\n" );
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document.write( "Reduce the common factor 28 in both sides; then cross multiply.  You will get\r\n" );
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document.write( "    2*(u-4) = u + 4\r\n" );
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document.write( "    2u - 8 = u + 4\r\n" );
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document.write( "    2u - u = 4 + 8\r\n" );
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document.write( "     u     = 12.\r\n" );
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document.write( "ANSWER.  The speed of the boat is 12 miles per hour in still water.\r\n" );
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