Triangles $PQR$ and $LMN$ are graphed in the xy-plane. Triangle $PQR$ has vertices $P$, $Q$, and $R$ at $\left(4,5\right)$, $\left(4,7\right)$, and $\left(6,5\right)$, respectively. Triangle $LMN$ has vertices $L$, $M$, and $N$ at $\left(4,5\right)$, $\left(4,7+k\right)$, and $\left(6+k,5\right)$, respectively, where $k$ is a positive constant. If the measure of $\angle Q$ is $t°$, what is the measure of $\angle N$?