document.write( "Question 1140355: In 2 1/2 hours an airplane travels 400 km against the wind. It takes 50 min to travel 200 km with the wind. Find the speed of the wind and the speed of the airplane in still air. \n" ); document.write( "

Algebra.Com's Answer #760856 by ikleyn(52790) $\"\"$ $\"About$

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document.write( " = 160 mph is the speed of the airplane against the wind, which is   u - v, \r\n" );
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document.write( "where u is the speed of the airplane in still air, v is the speed of the wind.\r\n" );
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document.write( "So, one equation is\r\n" );
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document.write( "    u - v = 160.    (1)\r\n" );
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document.write( " = 240 mph is the speed of the airplane with the wind, which is u + v.\r\n" );
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document.write( "So, the other equation is\r\n" );
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document.write( "    u + v = 240.    (2)\r\n" );
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document.write( "From equations (1) and (2)  you get (using elimination or substitution method)\r\n" );
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document.write( "u = 200 mph;   v = 40 mph.     ANSWER\r\n" );
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