document.write( "Question 1193095: A boat travels 120 miles downstream in the same time as it travels 105 miles upstream. The speed of the current is 7 mph. What is the speed of the boat? \n" ); document.write( "

Algebra.Com's Answer #825073 by ikleyn(52781) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "            There is NO such conception \"speed of the boat\", at all.\r
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\n" ); document.write( "\n" ); document.write( "            There is a conception \"speed of the boat relative to something\", instead.\r
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\n" ); document.write( "\n" ); document.write( "            In your case the question is about speed of the boat in still water.\r
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document.write( "Let x be the speed of the boat in still water.\r\n" );
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document.write( "Then the speed of the boat moving downstream is (x+7) mph;\r\n" );
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document.write( "                           moving upstream   is (x-7) mph.\r\n" );
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document.write( "Write the \"time\" equation\r\n" );
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document.write( "     = \r\n" );
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document.write( "Cross-multiply, simplify and find x\r\n" );
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document.write( "    120*(x-7) = 105*(x+7)\r\n" );
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document.write( "      8*(x-7) =   7*(x+7)\r\n" );
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document.write( "      8x - 56 =   7x + 49\r\n" );
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document.write( "      8x - 7x =   49 + 56\r\n" );
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document.write( "         x    =     105 mph,   which is quite unrealistic.\r\n" );
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\n" ); document.write( "\n" ); document.write( "You better throw this \"problem\" to the closest garbage bin.\r
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