Step-by-step explanation:
Let i, j and k represents east, north and upward direction respectively.
Velocity due north,

Velocity of the crosswind,

Velocity of downdraft,
(downward direction)
(a) Let v is the position vector that represents the velocity of the plane relative to the ground. It is given by :

(b) The speed of the plane relative to the ground can be calculated as :

v = 66 m/s
Hence, this is the required solution.