The correct answer to the question is : 10 m/s , northwest.
EXPLANATION:
As per the question, the velocity of wind V = 8 m/s towards north.
The velocity of the paper airplane is V' = 6 m/s towards west.
We are asked to calculate the actual velocity of the airplane.
By putting Pythagorean theorem, the actual velocity of the airplane is calculated as -

⇒ 
⇒ 
⇒ 
⇒
towards northeast.
Hence, the correct answer is 10 m/s , northwest.