s = plane's speed
w = wind speed
2800/(s-w) = 3.5
2800/(s+w) = 2.5
3.5s - 3.5w = 2800
2.5s + 2.5w = 2800
s = 960
w = 160
2800/800 = 3.5
2800/1120 = 2.5
A plane flies the first half of a 5600 km flight into the wind in 3.5 hours. The return trip, with the same wind, takes 2.5 hours. Find the speed of the wind and the speed of the plane in still air.
1 answer