Question

what is the measure, in degrees, of ∠abc?
90°
65°
77.5°
25°

Explanation:

Step1: Recall linear - pair property

The angle $\angle ABC$ and the $155^{\circ}$ angle are a linear - pair. The sum of angles in a linear - pair is $180^{\circ}$. Let $\angle ABC=x$. Then $x + 155^{\circ}=180^{\circ}$.

Step2: Solve for $x$

Subtract $155^{\circ}$ from both sides of the equation: $x=180^{\circ}-155^{\circ}$.
$x = 25^{\circ}$

Answer:

$25^{\circ}$