Answer:
m∠A=52°
Step-by-step explanation:
Because of the exterior angle theorem, m∠A+m∠B=105° (The exterior angle)
We then end up with an equation like this...
m∠A+m∠B=105°
Then, you do the substitution...
x+53°=105°
Subtract 53 from both sides...
x=105°-53°
x=52°
