document.write( "Question 903939: An airplane flies 400 miles against a headwind in 2 hours. The return trip with the same wind as a tailwind, takes 1 hour and 40 minutes. Find the plane's air speed and the wind speed. \n" ); document.write( "

Algebra.Com's Answer #548402 by mananth(16946) $\"\"$ $\"About$

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Plane speed =x mph
\n" ); document.write( "wind speed =y mph
\n" ); document.write( "against wind 2 hours
\n" ); document.write( "with wind 1 2/3 hours
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\n" ); document.write( "Distance against 400 miles distance with 400 miles
\n" ); document.write( "t=d/r against wind -
\n" ); document.write( "400 / ( x - y )= 2
\n" ); document.write( "2 ( x - y ) = 1 2/ 3
\n" ); document.write( "2 x - 2 y = 400 ....................1
\n" ); document.write( "
\n" ); document.write( "400 / ( x + y )= 1 2/ 3
\n" ); document.write( "1 2/ 3 ( x + y ) = 400
\n" ); document.write( "1 2/ 3 x + 1 2/ 3 y = 400 ...............2
\n" ); document.write( "Multiply (1) by 1 2/ 3
\n" ); document.write( "Multiply (2) by 2
\n" ); document.write( "we get
\n" ); document.write( "3 1/ 3 x + -3 1/ 3 y = 666 2/ 3
\n" ); document.write( "3 1/ 3 x + 3 1/ 3 y = 800
\n" ); document.write( "6 2/ 3 x = 1466 2/ 3
\n" ); document.write( "/ 6 2/ 3
\n" ); document.write( "x = 220 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "2 x -2 y = 400
\n" ); document.write( "440 -2 -440 = 400
\n" ); document.write( "-2 y = 400
\n" ); document.write( "-2 y = -40 mph
\n" ); document.write( " y = 20
\n" ); document.write( "Plane speed 220 mph
\n" ); document.write( "wind speed 20 mph
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\n" ); document.write( "m.ananth@hotmail.ca
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