Answer:
z = 61
Explanation:
The exterior angle is congruent (equal to) the sum of the 2 farthest angles from it, so you can set the equation like this:
z + z - 11 = z + 50
Add like terms, which would be the 2 "z's" on the left side:
2z - 11 = z + 50
Then subtract the z on the right side from both sides:
2z - 11 = z + 50
-z -z
___________
z - 11 = 50
Add 11 to both sides:
z - 11 = 50
+ 11 +11
________
z = 61