Question 762807
with a wind velocity of 40 kph, it takes an airplane as long to travel 1200 km with the wind as 900 km against it. how fast can the plane travel in still air?
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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
..
{{{1200/(x+40)=900/(x-40)}}}
1200(x-40)=900(x+40)
1200x-48000=900x+36000
300x=84000
x=280
speed of plane in still air=280 kph