document.write( "Question 553313: A plane left an airport and flew with the wind for 4 hours, covering 2000 miles. It then returned over the same route to the airport against the same wind in 5 hours. Find the rate of the plane in still air and the speed of the wind. \n" ); document.write( "

Algebra.Com's Answer #360788 by mananth(16946) $\"\"$ $\"About$

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Plane speed =x mph
\n" ); document.write( "wind speed speed =y mph
\n" ); document.write( "against wind x-y 5.00 hours
\n" ); document.write( "with wind x+y 4.00 hours
\n" ); document.write( "
\n" ); document.write( "Distance = same= 2000 miles
\n" ); document.write( "t=d/r
\n" ); document.write( "2000 / ( x - y )= 5.00
\n" ); document.write( "5 ( x - y ) = 2,000.00
\n" ); document.write( "5 x -5 y = 2000 ....................1
\n" ); document.write( "2000 / ( x + y )= 4.00
\n" ); document.write( "4.00 ( x + y ) = 2000
\n" ); document.write( "4.00 x + 4.00 y = 2000 ...............2
\n" ); document.write( "Multiply (1) by 4.00
\n" ); document.write( "Multiply (2) by 5.00
\n" ); document.write( "we get
\n" ); document.write( "20 x + -20 y = 8000
\n" ); document.write( "20 x + 20 y = 10000
\n" ); document.write( "40 x = 18000
\n" ); document.write( "/ 40
\n" ); document.write( "x = 450 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "5 x -5 y = 2000
\n" ); document.write( "2250 -5 y = 2000
\n" ); document.write( "-5 y = 2000 -2250
\n" ); document.write( "-5 y = -250
\n" ); document.write( " y = 50 mph
\n" ); document.write( " \n" ); document.write( "

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