Question

How do you find the angle measurement (in a easy explanation)

Answer 1

It depends. You can find it with a protractor, or if they give you an equation you can just solve for the variable they give you.

Answer 2

It really depends on the question.
If you didn't have any information on the surrounding angles, and thus you wouldn't be able to use algebra,
You would find an angle with a protractor.

However, if you were dealing with right angle triangles, (i'm aware you're in middle school), like in highschool, you could find an angle using trigonometry.