The pilot has to reach an airport due south that is 450 km away in 3 hours. There is a wind blowing from the west at 20 km/h.

The net velocity of the plane should be 150 km/h towards the south.

To cancel the velocity of the wind, the pilot should maintain the velocity of the plane at a speed of sqrt(150^2 + 20^2) = sqrt(22900) = 151.327 km/h.

The direction of the plane should be arc tan(20/150) = 7.59 degrees west of south.

The plane should be flown at 151.327 km/h in a direction 7.59 degrees west of south.