Answer:
12 Pieces left!
Explanation:
Because, Look. 6 is 1 quarter, He gave some of his other friends less.
If you add 2 + 4, thats 6! 6 is 1 quarter. There is 4 quarters in a cake. SO 6 + 6 12, thats half of a quarter. And then he gets the other half! Good luck!
(24 pieces in his cake)