document.write( "Question 325523: A plane flew 1200 miles with a tailwind in 2.5 hours. The return trip against the wind took 3 hours. Find the speed of the wind, find the speed of the plane in still air. \n" ); document.write( "
Algebra.Com's Answer #233128 by mananth(16946)\"\" \"About 
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Let speed of plane be xmph
\n" ); document.write( "speed of wind be y mph
\n" ); document.write( "..
\n" ); document.write( "with wind speed = x+y
\n" ); document.write( "distance = 1200
\n" ); document.write( "Time = 1200/x+y = 2.5
\n" ); document.write( "1200=2.5x+2.5y................1
\n" ); document.write( "..
\n" ); document.write( "Against wind speed = x-y
\n" ); document.write( "disatnce = 1200
\n" ); document.write( "time = 1200/x-y=3
\n" ); document.write( "1200= 3x-3y...............2
\n" ); document.write( "..
\n" ); document.write( "multiply equation 1 by 3 and equation 2 by 2.5
\n" ); document.write( "3600=7.5x+7.5y
\n" ); document.write( "3000=7.5x-7.5y
\n" ); document.write( "By adding the two equations
\n" ); document.write( "6600=15x
\n" ); document.write( "x=440 mph speed of plane
\n" ); document.write( "plug the value of x in the equation 2
\n" ); document.write( "1200= 1320-3y
\n" ); document.write( "3y=120
\n" ); document.write( "y= 40 mph speed of wind \n" ); document.write( "
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