document.write( "Question 184237: a plane makes a trip of 5040 km in 7h, flying with the wind. Returning against the wind, the plance makes the trip in 9h. What is the speed of the wind? \n" ); document.write( "
Algebra.Com's Answer #138331 by ptaylor(2198)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "Distance (d) equals Rate (r) times Time (t) or d=rt; r=d/t and t=d/r\r
\n" ); document.write( "\n" ); document.write( "let r =speed of the wind
\n" ); document.write( "And let s=speed of the plane in still air\r
\n" ); document.write( "\n" ); document.write( "With the wind: s+r=5040/7=720--------------eq1
\n" ); document.write( "Against the wind: s-r=5040/9=560------------------eq2
\n" ); document.write( "subtract eq2 from eq1:
\n" ); document.write( "2r=160
\n" ); document.write( "r=80 mph---------------------------speed of wind
\n" ); document.write( "from eq1
\n" ); document.write( "s+80=720
\n" ); document.write( "s=640--------------------------speed of plane in still air
\n" ); document.write( "CK
\n" ); document.write( "5040=(640+80)*7
\n" ); document.write( "5040=5040
\n" ); document.write( "and
\n" ); document.write( "5040=(640-80)*9
\n" ); document.write( "5040=5040\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor
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