A solid conducting sphere of radius 2.00 cm has a charge of 8.00 JC. A conducting spherical shell of inner radius 4.00 cm and outer radius 5.00 cm is concentric with the solid sphere and has a charge of -4.00 JC. Find the electric field at a) r= 1.00 cm, b) r= 3.00 cm, c) r= 4.50 cm, and d) r= 7.00 cm from the center of this charge configuration