Question

A and B are supplementary angles. If m A=(x-18)° and mB =(x-20),
find the measure of B

Answer 1

B = 89

Explanation:

Supplementary angles: A + B = 180

Simplify: x-18 +x -20 = 180

2x-38 = 180

2x = 218

x= 109

B = x-20

B = 89

Answer 2

89 degrees

Explanation:

supplementary angles add up to 180 degrees, so we can add up A and B and make it equal to 180.

(x-18)+(x-20)=180

2x-38=180

2x=218

x=109

then, we plug in 109 for x in the mB equation.

mB=x-20

mB=109-20

mB=89 degrees

therefore, the measure of B is 89 degrees.