A plane flies 440 km with the wind and 360 km against the wind in the same length of time. If the speed of the wind is 20 km/h, what is the speed of the plane in still air?  Choose one
A) 160 km/h	B) 170 km/h	C) 180 km/h	D) 190 km/h	E) 200 km/h
The speed of the plane in still air = x km/h   The speed of the wind is 20 km/h   Speed with the wind = (x + 20) km/h   Speed against the wind = (x â€“ 20) km/h   Time = Distance/ Speed   440 / (x+20) = 360 / (x-20)   440(x-20) = 360(x+20)   44x - 880 = 36x + 720   8x = 1600   x = 200   Therefore, the speed of the plane in still air is 200 km/h.   The answer is 200 km/h.
<result>E</result>
A plane flies 440 km with the wind and 360 km against the wind in the same length of time. If the speed of the wind is 20 km/h, what is the speed of the plane in still air?