A piece of paper flies upward for 6 km. At that time the wind is blowing at 10 km north and 8 km east. About how many km displacement has taken place from initial to final position?

The paper will fly in three dimensional space. So there are three displacement vectors associated. The net displacement will be the vector sum of the three.The displacement from tip of the 6 km vector to the head of the 8 km vector is 10 kilometers. Further 10 km vector is perpendicular to the other 10 km vector. Applying the Pythagorean theorem on the two 10 km vectors will give approximate 14 km.