Determining Electric Flux for cylindrical surfaces

[euphtone06]

1. The problem statement, all variables and given/known data
Cylin. surfaces \rho = 1 , 2 , 3, cm have uniform surface charge density of 20, -8, 5 nC/m^2.

What is the total electric flux that passes through the closed surface rho = 4 cm and z(from 0 to 1 m)?

And what is \vec{D} at the point \rho= 4 cm , \phi= 0 , z = .5 cm


2. Relevant equations
\Phi= E2piRL=\lambdaL/8.85x10-12
E = \rho/(2pi8.85x10^-12 \rho)


3. The attempt at a solution

So the closed surface from which to determine the flux is at \rho = .04 m

I frankly am unsure how to use the equations to get the total flux.

\Phi1 = 20(.01)/8.85x10^-12
\Phi2= -8(.02)/8.85x10^-12
\Phi3= 5(.03)/8.85x10^-12


Is it as simple as adding them all up? Or does the center most cylindrical surface at 1 cm have an affect on 2 cm surface which then in turn affects the 3 cm? I have a feeling this is completely wrong so I attempted it a different way

\int.04*20
\int.04*-8
\int.04*5
total flux = sum of the integrals?

I obviously am struggling with this concept any help would be appreciated Thanks!