Question

find the measure of the missing angle.

Explanation:

Step1: Recall angle - sum property

The sum of interior angles of a triangle is $180^{\circ}$.

Step2: Set up the equation

Let the missing angle be $x$. Then $x + 20^{\circ}+130^{\circ}=180^{\circ}$.

Step3: Solve for $x$

$x=180^{\circ}-(20^{\circ} + 130^{\circ})=180^{\circ}-150^{\circ}=30^{\circ}$.

Answer:

$30^{\circ}$