Answer:
∠3 = ∠4 = 60°
Step-by-step explanation:
Angles 1 and 3 are "remote interior angles" with respect to angle 2, so ...
∠2 = ∠1 + ∠3
120° = 60° + ∠3 . . . fill in known values
60° = ∠3 . . . . . . . . . subtract 60°
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Since two of the interior angles in the triangle ABC are 60°, the third one is also. The interior angle at B (supplementary to angle 2) is corresponding to ∠4, so has the same measure as angle 4.
∠4 = 60°
