What is the measure of B?

∠B = 82°

Step-by-step explanation:

To find the measure of B, you have to find the measure of A.

m∠143° + m∠A = 180° because they are a linear pair

m∠A + 143 = 180

Subtract both sides by 143

m∠A = 37

Since you know the measure of angle A, you can find angle B

Angle A, B, and C should add up to 180° as triangles' angles sum up to 180°.

∠B + ∠A + ∠C = 180°

Substitute

∠B + 37 + 61 = 180

∠B + 98 = 180

Subtract 98 from both sides

∠B = 82°

step-by-step explanation: