Recently Blake had a party and because it was their birthday they wanted a mathematical cake.
Blake ordered a cake in the shape of a cube, and had it completely iced (but of course they didn't ice the underneath because that just isn't very sensible).
Blake cut every side of the cake into three equal pieces, giving 27 slices of cake.
Blake wanted to eat all of the pieces of cake that had exactly 2 sides with icing.
So, how many pieces did that leave for the guests?