Answer:
m∠A=30°
Step-by-step explanation:
we know that
Vertical Angles are the angles opposite each other when two lines cross.
Vertical angles always are congruent
In this problem
m∠A=m∠B ----> by vertical angles
we have
m∠A=x
m∠B=3x-60
substitute
[tex]3x-60=x[/tex]
Solve for x
[tex]3x-x=60[/tex]
[tex]2x=60[/tex]
[tex]x=30[/tex]
therefore
m∠A=30°