Question

1. find the missing angle measure

Explanation:

Step1: Recall angle - sum property of quadrilateral

The sum of interior angles of a quadrilateral is $360^{\circ}$. Let the missing angle be $\angle W$.

Step2: Set up the equation

$\angle W+100^{\circ}+80^{\circ}+100^{\circ}=360^{\circ}$.

Step3: Solve for the missing angle

$\angle W=360^{\circ}-(100^{\circ}+80^{\circ}+100^{\circ})=360^{\circ}-280^{\circ}=80^{\circ}$.

Answer:

$80^{\circ}$