Three point charges are positioned on the x axis. If the charges and corresponding positions are +32 µC at x = 0, +20 µC at x = 40 cm, and –60 µC at x = 60 cm, what is the magnitude of the electrostatic force on the +32-µC charge?

The magnitude of the electrostatic force on is:  

Explanation:

Consider

The sum of all horizontal forces on is given as

where

The force on exerted by is repulsive, so the direction of the force is to the left (negative direction). Thus

The force on exerted by is attractive, so the direction of the force is to the right (positive direction). Thus

Therefore

the electrostatic force on is to the right and has a magnitude of

the answer is b i think