Answer:
B
Step-by-step explanation:
The interior angles of a triangle always add up to 180 degrees.
We have two angles already and they add up to 60+63=123 degrees
180-123=57
so the remaining angle is 57 degrees
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D. 123°
The external angle is equal to the sum of the remote internal angles.
m∠1 = 60° +63°
m∠1 = 123°
