QUIZ 1
   (Z)

   |-|                (A)        (B)         (C)
  /   \
 /     \                15      7 - 15        7
7      |/|         7 - ----    --------    -------
      /   \             60        60       15 - 60
     /     \
    15     60

(Z)  -->  (A) | (B) | (C) ?
(Z) -->