Answer:
z = 7
Step-by-step explanation:
4z - 8 = 20
Add 8 to each side
4z - 8+8 = 20+8
4z = 28
Divide each side by 4
4z/4 = 28/4
z = 7
28.333333333. If you do a proportion and place it 1/(?) times .6/(17) you should multiply 17 by 1 (17*1) which should equal 17. You now have to divide it so 17 divided by .6 (17/6) which equals to 28.333333.
Its the second one. Everything is by a quarter. Its an octagon. Shouldnt be to difficult

Actually Welcome to the Concept of the Triangle
Angle sum property.
We have to use here the Exterior Angle theorem of a triangle, so we get as ,
Angle ACD = 113°