With the wind, a jet can fly 2500km in 2 hours 30 min.
With wind DATA:
distance = 2500 km ; time = 2.5 hrs ; rate = 2500/2.5 = 100 km/h
Against the wind, it can fly only 2000km in the same time.
Against wind DATA:
distance = 2000 km ; time = 2.5 hrs ; rate = 2000/2.5 = 800 kmh
Find the rate of the jet in still air and the rate of the wind.
p + w = 100
p - w = 80
2p = 180
p = 90 kmh (plane speed in still air)
Since p+w = 100, w = 10 kmh (wind speed)