Two metal spheres, each of radius 3.0 cm, have a center-to-center separation of 2.0 m

Two metal spheres, each of radius 3.0 cm, have a center-to-center separation of 2.0 m. Sphere 1 has charge +1.0×10−8C; sphere 2 has charge −8.0×10−8C. Assume that the separation is large enough for us to say that the charge on each sphere is uniformly distributed (the spheres do not affect each other). With V = 0 at infinity, calculate

a) the potential at the point halfway between the centers and the potential on the surface of
b) sphere 1 and
c) sphere 2.