Answer:
a =18
Step-by-step explanation:
The two angles are vertical angles and vertical angles are equal
6a +11 = 2a+83
Subtract 2a from each side
6a-2a +11 = 2a-2a+83
4a +11 =83
Subtract 11 from each side
4a +11 -11 = 83-11
4a = 72
divide each side by 4
4a/4 = 72/4
a =18
