Answer:
5.
x + y + z = 180 degrees
a = b (true)
c = z
6.
a + c = 180 degrees
x + y = a
Step-by-step explanation:
5.
The Sum of all angles in a triangle is 180 degrees
a = b because it is vertical angle, and also c = z too
6.
a + c = 180 because it is supplementary angle
x + y = a (An exterior angle of a triangle is equal to the sum of the two opposite interior angles.)