A solid non$-$conducting sphere with radius $0\mathrm{.}5$ m and a uniform charge

distribution is surrounded by a thick conducting shell, with an inner radius of $2$ m

and outer radius of $2\mathrm{.}5$ m$.$ If the total charge on the inner sphere is $2$ C and the total

charge on the outer sphere is $-4$ C$,$ what is the magnitude and direction of the

electric field at a distance $3$ m from the common center of the spheres?