Question

Find the measure of an angle whose supplement measures eight times its measure

Answer 1

The supplement of an angle is basically 180° minus that angle. In other words, two supplementary angles together add up to 180°.

If you let $x$ be the angle, then $x$ plus an angle eight times its measure is equal to 180°. Thus, $x + 8x = 180$, or $9x = 180$. Therefore, $x$ = 20°.