The x-y plane separates dielectric material with εr1=2.0 (for z<0) from dielectric material with εr2=4.0 (for z<0). In medium 1 we have electric flux density D1=1.0ax+8.0ay+4.0az nC/m2. There is a sheet charge ρs=1.0 nC/m2 at the interface between the two dielectrics. Determine the flux density D2.