can some one help with this formula please i need to find 2 unknowns

A area and d distance

Formula is

C = Er*Eo*A / d

where

C= 100x10 power-12

Er=12

Eo= 8.85x10power-12

i can isolate d/A to equal Er*Eo/C which makes d/A = 1.062 ohms

and get d= Er*Eo*A / C

but brain wont go any further

any help much appreciated

thanks Ian