<PRE><B>Question 435325</B>
an airplane flies 500 miles with the wind and 340 miles against the wind in the same length of time. If the speed of the wind is 40, what is the speed of the airplane in still air
..
let x=speed of plane in still air
(x+40)=speed of plane with the wind
(x-40)=speed of plane against the wind
Travel time = distance/speed
500/(x+40)=340/(x-40)
500(x-40)=340(x+40)
500x-20000=340x+13600
160x=33600
x=210
ans:
speed of the airplane in still air=210 mph</PRE>