What is the value of z? Please provide an explanation, thanks!

Answer:
z=7
Step-by-step explanation:
72°+(8z-8)°+(9z-3)°=180° (a triangle contains 180° and vertical angles are equal)
(8z-8)°+(9z-3)°=180°-72°
17z°-11°=108°
17z°=108°+11°
17z°=119°
z°=119°/17°
z°=7°
z=7