Answer:
b°+90°=180°(sum of angle in straight line)
b°=180°-90°
b°=90°
a°=30°(vertically opposite angle)
A: 30 degrees
B: 60 degrees
C:105 degrees
Step-by-step explanation:
A: vertical angles are congruent
B: solve for the missing angle -- 90+30+?=180
C: Use exterior angle to find the supplementary angle
