Question

17. ∠a and ∠b are supplementary. If m∠a = 2x + 1 and m∠b = 3x - 6, what is the measure of ∠b?

A.35°
B.37°
C.71°
D.105°

Answer 1

supplementary angles are two angles, when added, equal 180 degrees.
so if <a and <b are supplementary, then they equal 180 degrees.
2x + 1 + 3x - 6 = 180 -- combine like terms
5x - 5 = 180 -- add 5 to both sides
5x = 185 -- divide both sides by 5
x = 37

<b = 3x - 6
<b = 3(37) - 6
<b = 111 - 6
<b = 105 degrees

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