The letters are placed in the sets A, B and C as shown. How many letters belong to B or C but not to A?

Outside A but inside B or C: k (B only), m and $x$ (C only), d and $y$ (B and C only) — 5 letters. 6 wrongly takes w, which is also in A, 8 counts every letter in B or C, and 3 counts the regions instead of the letters.