Answer:
∠3 = 100°
∠2 = ∠4 = 80°
Explanation:
You want the measures of the four angles where lines m and n cross, given that obtuse angle 1 is 100°.
Vertical angles
Vertical angles 1 and 3 are congruent.
∠3 = 100°
Linear pair
Adjacent angles of a linear pair are supplementary:
∠2 = ∠4 = 180° -100°
∠2 = ∠4 = 80°
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Additional comment
Angles 2 and 4 are also vertical angles, congruent to each other.