Answer:
81
Step-by-step explanation:
From the diagram,
143 is the exterior angle of the triangle.
61 and B are interior angles of the triange.
Formula : -
Exterior angle of a triangle = Sum of two interior angles in a triangle
143 = 61 + ∠B
∠B = 143 - 61
∠B = 82
Therefore, the measure of ∠B is 82.
