Capacitors Electrostatic energy

A metal sphere of radius R is charged to a potential V.
a.)Find the electrostatic energy stored in the electric field within a concentric sphere of radius 2R
b.) Show that the electrostatic energy stored outside the sphere of radius 2R equals that stored within it

Due to the problem with the mathematical symbols, I could not solve this question here. But I have uploaded the solution at the link:

https://sites.google.com/site/physicsato…

Solution12.pdf