document.write( "Question 487844: A plane traveled 416 miles to Des Moines and back. The trip there was with the wind. It took 4 hours. The trip back was into the wind. The trip took 8 hours. Find the speed of the plane in still air and the speed of the wind. \n" ); document.write( "
Algebra.Com's Answer #333161 by lwsshak3(11628)\"\" \"About 
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A plane traveled 416 miles to Des Moines and back. The trip there was with the wind. It took 4 hours. The trip back was into the wind. The trip took 8 hours. Find the speed of the plane in still air and the speed of the wind.
\n" ); document.write( "***
\n" ); document.write( "Let x=speed of plane in still air
\n" ); document.write( "Let w=speed of wind
\n" ); document.write( "Speed of plane downwind=x+w
\n" ); document.write( "Speed of plane into wind =x-w
\n" ); document.write( "Travel time= distance/speed
\n" ); document.write( "2 Equations:
\n" ); document.write( "Downwind:
\n" ); document.write( "416/x+w=4
\n" ); document.write( "4x+4w=416
\n" ); document.write( "Into wind:
\n" ); document.write( "416/x-w=8
\n" ); document.write( "8x-8w=416
\n" ); document.write( "multiply first equation by 2
\n" ); document.write( "8x+8w=832
\n" ); document.write( "add first and second equations
\n" ); document.write( "16x=1248
\n" ); document.write( "x=78
\n" ); document.write( "Using first equation:
\n" ); document.write( "4x+4w=416
\n" ); document.write( "4w=416-4x=416-312=104
\n" ); document.write( "w=26
\n" ); document.write( "..
\n" ); document.write( "ans:
\n" ); document.write( "speed of plane in still air=78 mph
\n" ); document.write( "wind speed=26 mph \n" ); document.write( "
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