ANSWER:
119°
The measure of angle B in degrees is 119°.
STEP-BY-STEP EXPLANATION:
To find angle B, we will first find angle A.
The sum of the two interior angles which don't share a vertex with the respective exterior angle are equivalent to the respective exterior angle.
THEREFORE:
Let angle A = A
A + 51 = 112
A = 112 - 51
A = 61°
A and B together form a straight angle. A straight angle is equivalent to 180°.
THEREFORE:
Let angle B = B
A + B = 180°
61 + B = 180
B = 180 - 61
B = 119°
