Answer:
y = 48°
Explanation:
The value of an inscribed angle is half the value of the arc it subtends.
The angle marked x subtends the arc marked 66°, so has a value of ...
x = 66°/2
x = 33°
The value of y is similarly found.
y = 96°/2
y = 48°
The angle marked with a dot is an external angle of the triangle, so is the sum of the remote internal angles, x and y:
dot angle = x + y = 33° +48° = 81°
Of course, angle z is the supplement of this:
z = 180° -81°
z = 99°