Answer:
The value of the z is 12 .
Step-by-step explanation:
Definition of vertically opposite angle .
Vertically opposite angles is defines angles opposite to each other when two lines cross eachother .
Thus
(5z + 8)° = (4z + 20)°
(5z + 8) = (4z + 20)
Open the bracket
5z + 8 = 4z + 20
5z - 4z = 20 -8
z = 12
Therefore the value of the z is 12 .