Answer:
m∠ABC = 45°
Step-by-step explanation:
See the attached figure.
As shown in the figure
Line C B extends through point D to form the exterior angle that is 135 degrees.
So, m∠ABD = 135°
But m∠ABC + m∠ABD = 180°
∴m∠ABC = 180° - m∠ABD = 180° - 135°= 45°
Also, we should know that
m∠ABD = m∠BAC + m∠ACB
So, m∠ACB = 135° - 75° = 60°
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<u>Very important note:</u>
If we replaced the location of B and C
SO, m∠ABC = 60° and m∠ACB = 45°
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