The space between two concentric conducting spherical shells of radii b = 2.10 cm and a = 1.20 cm is filled with a substance of dielectric constant K = 20.8. A potential difference V = 52.0 V is applied across the inner and outer shells. Determine (a) the capacitance of the device, (b) the free charge q on the inner shell, and (c) the charge q induced along the surface of the inner shell.