A particle $)=(+40nC$ is located on the $x$ axis at the point $x=-20m,$ and a second particle $=-50nC)$ is placed on the $x$ axis at $x=+30m.$ What is the magnitude of the total electric potential at the origin $)=(0?$

Select one:

a$.-15$ volt

b$.3$ volt

c$.18$ volt

d$.-3$ volt