Two spherical shells have a common center. A $-3\mathrm{.}00{10}^{-6}C$ charge is spread uniformly over the inner shell, which has a

radius of $0\mathrm{.}050m.$ A $+5\mathrm{.}00{10}^{-6}C$ charge is spread uniformly over the outer shell, which has a radius of $0\mathrm{.}15m.$ Find the

magnitude and direction of the electric field at a distance $($measured from the common center$)$ of

$($a$)0\mathrm{.}20m,$

$E=$

$($b$)0\mathrm{.}10m,$

$E=$

$($c$)0\mathrm{.}025m.$

$E=$

Dont forget Units please