A cylindrical metal shell having inner and outer radii of 0.200m and 0.300m, correspondingly, carries a total charge of around 4.0 x 10^-8 C/m. All along its center there is a wire having a uniform charge of -12.0 x 10^-8 C/m. (This system is identical to an electrostatic air cleaner.)
Evaluate the electric potential caused by the system of electric charges, by using the outer surface of the shell as a reference point for the potential.