A nonconducting solid sphere of radius a with its center at the origin has a spherical cavity

Question:

A nonconducting solid sphere of radius a with its center at the origin has a spherical cavity of radius b with its center at the point x = b, y = 0 as shown in Figure. The sphere has a uniform volume charge density ?. Show that the electric field in the cavity is uniform and is given by Ey = 0, Ex = ?b/3?0.