document.write( "Question 1143008: A plane can fly 255 miles downwind in the same amount of time as it can travel 165 miles upwind. Find the velocity of the wind if the plane can fly 210 mph in still air. \n" ); document.write( "

Algebra.Com's Answer #763760 by math_helper(2461) $\"\"$ $\"About$

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document.write( "Let  w = wind speed\r
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document.write( "(1)  (210 + w)t = 255  --->   210t + wt = 255   --->  wt = 255-210t
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document.write( "(2)  (210 - w)t = 165  --->   210t - wt = 165 \r
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document.write( "Subs for wt (rightmost derivation of eq (1)) into (2):\r
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document.write( "   210t - (255-210t) = 165
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document.write( "   420t = 420  
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document.write( "      t = 1hr  --> (using (1)) --> (210+w)(1) = 255 -->   mi/hr\r
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