Question

1 the measure of an angle is $159^\circ$.
what is the measure of its supplementary angle?
a $21^\circ$
b $69^\circ$
c $180^\circ$
d $59^\circ$

Explanation:

Step1: Define supplementary angles

Supplementary angles sum to $180^\circ$.

Step2: Calculate unknown angle

Let $x$ = supplementary angle.
$x = 180^\circ - 159^\circ$
$x = 21^\circ$

Answer:

A. $21^\circ$