The drawing shows four point charges. The value of q is 3.9 μC, and the distance d is 0.94 m. Find the total potential at the location P. Assume that the potential of a point charge is zero at infinity.

Hm' good question. What did you calculate the answer to b?

Then we will help. We do not do homework for anyone.

This is what I got -1864946.809 but it is not the right answer.