Question

which angle number represents an angle vertical to $\angle psl$?

Explanation:

Vertical angles are pairs of non-adjacent angles formed by two intersecting lines, opposite each other with equal measure. First, identify that $\angle PSL$ is formed by the intersection of lines $LP$ and $MN$ at point $S$. The angle opposite to $\angle PSL$ (non-adjacent, formed by the same two intersecting lines) is $\angle MSN$, which is labeled as $\angle 6$.

Answer:

$\angle 6$