please solve a question?

can anyone of u genius people provide me with the derivation of a relation of computing capacitance given on engineering electromagntics william h. hayt 6th edition question 6.3 or atleast give me some suggetions for deriving the required relation but anyway solution to derivation will be much more helpful

i need it in the nick of time within 12 or maximum of 20 hours from now

i will be highly greatful to u

hi,
solution manuals shud be available just search
thanx