You're walking in one direction, and then the exact opposite of that direction, so you simply have to subtract the two distances.
200-150=50
You're 50 meters west of where you originally started.
You're west because 200 meters west is greater than 150 meters east. If the distance walked east was greater than the distance walked west, you would've been east of your starting position.
Answer:

Explanation:
Let the sphere is uniformly charge to radius "r" and due to this charged sphere the electric potential on its surface is given as

now we can say that


now electric potential is given as


now work done to bring a small charge from infinite to the surface of this sphere is given as


here we know that

now the total energy of the sphere is given as




so, question number 10 answer is 82 watts