Problem $24\mathrm{.}47$

A solid conducting sphere of radius $2\mathrm{.}00$ cm has a charge of $8\mathrm{.}00C.$ A conducting spherical shell of inner radius $4\mathrm{.}00$ cm and outer radius $5\mathrm{.}00$ cm is concentric with the solid sphere and has a charge of $24\mathrm{.}00C.$ Find the electric field at $($a$)r=1\mathrm{.}00cm,($b$)r=3\mathrm{.}00cm,($c$)r=4\mathrm{.}50cm,$ and $($d$)r=7\mathrm{.}00cm$ from the center of this charge configuration.