document.write( "Question 720831: Against the wind a commercial airline in South America flew 340 miles in 2.5 hours With a tailwind the return trip took 2 hours. What was the speed of the airplane in still air? What was the speed of the wind? thank you for answering!! \n" ); document.write( "

Algebra.Com's Answer #442000 by mananth(16946) $\"\"$ $\"About$

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Plane speed =x mph
\n" ); document.write( "wind speed =y mph
\n" ); document.write( "against wind 2.5 hours
\n" ); document.write( "with wind 2 hours
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\n" ); document.write( "Distance with wind 340 miles distance against wind 340
\n" ); document.write( "t=d/r against wind (x-y)
\n" ); document.write( "340.00 / ( x - y )= 2.50
\n" ); document.write( "
\n" ); document.write( "2.50 x - -2.50 y = 340.00 ....................1
\n" ); document.write( "with wind (x+y)
\n" ); document.write( "340.00 / ( x + y )= 2.00
\n" ); document.write( "2.00 ( x + y ) = 340.00
\n" ); document.write( "2.00 x + 2.00 y = 340.00 ...............2
\n" ); document.write( "Multiply (1) by 2.00
\n" ); document.write( "Multiply (2) by 2.50
\n" ); document.write( "we get 2.00
\n" ); document.write( "5.00 x + -5.00 y = 680.00
\n" ); document.write( "5.00 x + 5.00 y = 850.00
\n" ); document.write( "10.00 x = 1530.00
\n" ); document.write( "/ 10.00
\n" ); document.write( "x = 153 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "2.5 x -2.5 y = 340
\n" ); document.write( "382.5 -2.5 -382.5 = 340
\n" ); document.write( "-2.5 y = 340
\n" ); document.write( "-2.5 y = -42.5 mph
\n" ); document.write( " y = 17
\n" ); document.write( "Plane 153 mph
\n" ); document.write( "wind 17 mph
\n" ); document.write( " \n" ); document.write( "

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