With the wind a jet can fly 2500km in 2 hours 30 min Against

With the wind a jet can fly 2500km in 2 hours 30 min. Against the wind, it can fly only 2000km in the same time. Find the rate of the jet in still air and the rate of the wind.

Solution

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 kmh
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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
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Find the rate of the jet in still air and the rate of the wind.
p + w = 100
p - w = 80
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2p = 180
p = 90 kmh (plane speed in still air)
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Since p+w = 100, w = 10 kmh (wind speed)