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From the solution by @MathLover1, it is clearly seen that
she DOES NOT KNOW basic terms, notions and definitions of Geometry
Her solution has nothing in common with the truth.
I came to bring a correct solution.
Let me start from the proper definition
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| Alternate interior angles are angles formed when two parallel |
| are intersected by a transversal. |
| The angles are positioned at the inner corners of the intersections |
| and lie on opposite sides of the transversal. |
+-------------------------------------------------------------------------+
One of the first theorem of Geometry states that alternate interior angles at two parallel lines are CONGRUENT,
i.e. have equal angular measure.
It means that A = B, or
2x = x + 30.
From this equation
x = 30 degrees.
So, both angles A and B have equal measure of 2*30 = 60 degrees = 30+30 degrees. ANSWER
Solved.
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About parallel lines and associated angles see the lesson
- Parallel lines
in this site.
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@MathLover1 re-wrote her solution after reading my post.
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