Triangles $△MNP$ and $△QRS$ are similar, where $M$ corresponds to $Q$, $N$ to $R$, and $P$ to $S$. If $m\angle M=(y+10{)}^{\circ }$, $m\angle N=(2y-5{)}^{\circ }$, and $m\angle S=(y+15{)}^{\circ }$, what is the measure of angle $P$?