A&Bsolved I need assistance with C&D? A point charge of +7.0 nC is fixed at position (0.0 , 5.0) m. A second point charge of -2.0 nC is fixed at position (-3.0 , 0.0) m. (a) Calculate the electric field (magnitude and direction) at position (0.0, 0.0) m. (b) Calculate the electric potential at...