Answer:
x = 20°
y = 160°
z = 160°
Explanation:
x = 20°
(Measure of arc is equal to the measure of its corresponding central angle) 
z = 180° - 20° 
(Linear pair angles) 
z = 160°
y = z 
(Measure of arc is equal to the measure of its corresponding central angle) 
y = 160°