document.write( "Question 1127374: A boat is traveling in a river that is flowing downstream at a speed of 5 kilometers per hour. The boat can travel 30 kilometers upstream in the same time it would take to travel 40 kilometers downstream. What is the speed of the boat in still water? \n" ); document.write( "

Algebra.Com's Answer #743770 by ikleyn(52852) $\"\"$ $\"About$

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document.write( "Let \"x\" be the speed of the boat in still water, in kilometers per hour.\r\n" );
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document.write( "Then its speed relative the bank of the river is x+5 km/h downstream and (x-5) km/h upstream.\r\n" );
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document.write( "The time equation is\r\n" );
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document.write( "     = .\r\n" );
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document.write( "    30*(x+5) = 40*(x-5)\r\n" );
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document.write( "    30x + 150 = 40x - 200\r\n" );
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document.write( "    150 + 200 = 40x - 30x\r\n" );
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document.write( "    10x = 350  ====>  x = 350/10 = 35.\r\n" );
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document.write( "Answer.  The boat speed in still water is  35 km/h.\r\n" );
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