Question

find the measure of the missing angles.
answer
b =
c =

Explanation:

Step1: Use vertical - angle property

Vertical angles are equal. Angle $b$ and the $123^{\circ}$ angle are vertical angles. So $b = 123^{\circ}$.

Step2: Use supplementary - angle property

The sum of adjacent angles that form a straight - line is $180^{\circ}$. Angle $c$ and the $123^{\circ}$ angle are adjacent and form a straight - line. So $c=180 - 123$.
$c = 57^{\circ}$

Answer:

$b = 123^{\circ}$, $c = 57^{\circ}$