physics
posted by Nick .
After flying for 15 min in a wind blowing 42 km/h at an angle of 20° south of east, an airplane pilot is over a town that is 42 km due north of the starting point. What is the speed of the airplane relative to the air?

The ground velocity of the airplane is 168 km/hr in a northern direction. This equals the vector sum of the plane's velocity with respect to the air, PLUS the air speed with repect to the land.
Therefore you will need to subtract the air velocity from the ground velocity of the plane to get the plane's speed (and direction) with respect to the air. 
it would be idk