119°
Step-by-step explanation:
for this angle A has to be found for that you can use the theorem that states sum of interior angles is equal to the sum of opp exterior angle
51 + A = 112
A = 112 - 51
A = 61°
THEN WE CAN FIND THE B angle
they are angles on a straight line
so 61 + B = 180
B = 119°
