PHYSICS
posted by Kara .
A capacitor consists of a solid metal sphere of radius 3 cm placed at the center of a thin metal spherical shell of radius 12 cm. The space between is empty. What is the capacitance?

For the solution to this problem (and the formula to use for C), see
http://hyperphysics.phyastr.gsu.edu/hbase/electric/capsph.html
You will need the value of epsilonzero, which I presume you have learned. 
Thank you so much for your help! I got the answer.