## Prealgebra (7th Edition)

$\angle x=155^{\circ}$ $\angle y=155^{\circ}$ $\angle z=25^{\circ}$
In the picture, we can see that $\angle x$ and the other angle ($25^{\circ}$) form a straight angle, they are supplementary angles, so they add up to $180^{\circ}$. $\angle x+25^{\circ}= 180^{\circ}$ $\angle x= 180^{\circ}-25^{\circ}$ $\angle x= 155^{\circ}$ The same is true with $\angle z$: $\angle y= 155^{\circ}$ If we consider $\angle z$ and $\angle y$, they are also supplementary angles, so they add up to $180^{\circ}$ $\angle z+\angle y=180^{\circ}$ $\angle z+155^{\circ}=180^{\circ}$ $\angle z= 180^{\circ}-155^{\circ}$ $\angle z=25^{\circ}$