document.write( "Question 654006: An airplane, flying at top cruising speed, travels 1,680 miles in 6 hours with the wind. Against the wind, the airplane takes 7 hours at top cruising speed to travel this same distance. The wind speed is constant. What is the top cruising speed of the airplane? \n" ); document.write( "
Algebra.Com's Answer #408587 by lwsshak3(11628)\"\" \"About 
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An airplane, flying at top cruising speed, travels 1,680 miles in 6 hours with the wind. Against the wind, the airplane takes 7 hours at top cruising speed to travel this same distance. The wind speed is constant. What is the top cruising speed of the airplane?
\n" ); document.write( "**
\n" ); document.write( "let x=top cruising speed of airplane
\n" ); document.write( "let c=wind speed
\n" ); document.write( "x+c=speed of plane with the wind
\n" ); document.write( "x-c=speed of plane against the wind
\n" ); document.write( "distance/speed=travel time
\n" ); document.write( "..
\n" ); document.write( "1680/(x+c)=6
\n" ); document.write( "1680/(x-c)=7
\n" ); document.write( "..
\n" ); document.write( "6x+6c=1680
\n" ); document.write( "7x-7c=1680
\n" ); document.write( "..
\n" ); document.write( "42x+42c=7*1680
\n" ); document.write( "42x-42c=6*1680
\n" ); document.write( "add
\n" ); document.write( "84x=1680(7+6)
\n" ); document.write( "84x=1680*13=21840
\n" ); document.write( "x=21840/84=260 mph
\n" ); document.write( "top cruising speed of airplane=260 mph\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
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