The drawing shows four point charges. The value of q is 2.4 µC, and the distance d is 0.86 m. Find the total potential at the location P. Assume that the potential of a point charge is zero at infinity.

This is a question of electric potential difference created by point charges.

To give a visual picture of the drawing in the question line #1 is drawn diagonally at about 45 degrees increasing in height from left to right. At each end of the line is a circle with "-q" in it. Line #2 is perpendicular to Line #1 and touches the halfway point of Line #1 at "P". The free end of Line #2 and the midway point both have a cirle with "q" in it. On line #1 "d" is the distance between "-q" and "P", "P" and the "-q" of the opposite end. On Line #2"d" is the distance between "q" on the unattached end and the "q" in the center, and from "q" in the center and "P".