In the given diagram, the measure of angle B (m∠B) is 40°
Exterior angle theorem
From the question, we are to determine the measure of angle B
By the exterior angle theorem,
The exterior angle of a triangle is equal to the sum of the two opposite interior angles.
Then, we can write that
m∠A + m∠B = 155° (Exterior angle theorem)
115° + m∠B = 155°
m∠B = 155° - 115°
m∠B = 40°
Hence, the measure of angle B (m∠B) is 40°
Learn more on Exterior angle theorem here: https://brainly.com/question/26772685
#SPJ1
