The Vertical Angles Theorem states that if two angles are vertical angles, then they are congruent .Given <A and <B are vertical angles so they are equal.
<A=<B.
Measure of <A=x and <B=5x-80
Or 5x-80=x
Adding 80 both sides
5x-80+80=x+80
5x=x+80
Subtracting x both sides
5x-x=x-x+80
4x=80
Dividing both sides by 4
x=20
Measure of <A= x= 20 degrees.
No, i would stay with my answer #1 and trust myself.
