Can a quadrilateral $\mathrm{A}\mathrm{B}\mathrm{C}\mathrm{D}$ be a parallelogram, if: $\mathrm{\angle }\mathrm{D}+\mathrm{\angle }\mathrm{B}=180°$?
 

The adjacent figure $\mathrm{H}\mathrm{O}\mathrm{P}\mathrm{E}$ is a parallelogram. Find the angle measures $\mathrm{x},\mathrm{y}$ and $\mathrm{z}.$ State the properties you use to find them.

The following figure $\mathrm{R}\mathrm{U}\mathrm{N}\mathrm{S}$ is a parallelogram, Find $\mathrm{x}$ and $\mathrm{y}$. (Length are in $\mathrm{c}\mathrm{m}$)