Sum 12 boxes = One case

Hey guys and gals, i have a quick question on how to set up a formula. My Wife is the "Cookie Mom" for my daughters Girl Scout troop. I'm trying to set her up a spread sheet that helps with totals of boxes sold at booths. There are 12 boxes in one Case. I want to have on her spread sheet how many cases and boxes are left. Example they sell 30 Boxes of cookies. I would like in the next cell to show 2.6 cases for 2 cases 6 boxes. Is there a way to do this or am i wishful thinking lol