P$43.$ The figure shows a section through $2$ long concentric cylinders of radii $3\mathrm{.}5cm$ and $7cm.$

The cylinders have equal and opposite charges per unit length of $10\frac{C}{m}.$ Along the common

axis runs a wire with an equal positive charge per unit length. Find the electric field at a radial

distance $r=0\mathrm{.}4cm$ from the central axis. $lo{n}_0=8\mathrm{.}85{10}^{-12}F*m^{-1}*(44\mathrm{.}959E12\frac{N}{C})$