Question

look at this diagram: if $overleftrightarrow{qs}$ and $overleftrightarrow{tv}$ are parallel lines and $mangle qru = 120^{circ}$, what is $mangle sru$?

Explanation:

Step1: Recall linear - pair property

$\angle QRU$ and $\angle SRU$ form a linear - pair. The sum of angles in a linear - pair is $180^{\circ}$.

Step2: Set up the equation

Let $m\angle QRU = 120^{\circ}$ and $m\angle SRU=x$. Then $m\angle QRU + m\angle SRU=180^{\circ}$, so $120^{\circ}+x = 180^{\circ}$.

Step3: Solve for $x$

Subtract $120^{\circ}$ from both sides of the equation: $x=180^{\circ}- 120^{\circ}=60^{\circ}$.

Answer:

$60$