Answer:
z = 99°
Explanation:
y = 0.5 × 96° = 48° ( inscribed angle subtended on same arc )
x = 0.5 × 66° = 33° ( inscribed angle subtended on same arc )
The sum of the 3 angles in the triangle = 180°, hence
third angle = 180° - (48 + 33)° = 180° - 81° = 99°
z = 99° ( vertical angle )
Check
96° + 99° + 66° + 99° = 360°