The figure shows two nonconducting spherical shells fixed in place. Shell 1 has uniform surface charge density +6.0 microC/m^2 on its outer surface and radius 3.0 cm; shell 2 has uniform surface charge density +4.0 microC/m^2 on its outer surface and radius 2.0 cm; the shell centers are separated by L = 10 cm. In unit-vector notation, what is the net electric field at x = 2.0 cm?