In the above figure, point $P$ is at distance $d_{1}=4.00m$ from particle 1 $(q_{1}=−2e)$ and distance $d_{2}=2.00m$ from particle 2 $(q_{2}=+2e)$, with both particles fixed in place. (a) With $V=0$ at infinity, what is $V$ at $P$? If we bring a particle of charge $q_{3}=+2e$ from infinity to $P$, (b) how much work do we do and (c) what is the potential energy of the three-particle system?