SAT Right triangles Question

Triangles PQR and LMN are graphed in the xy-plane. Triangle PQR has vertices P, Q, and R at $5,2$, $5,4$, and $7,2$, respectively. Triangle LMN has vertices L, M, and N at $5,2$, $5,4+k$, and $7+k,2$, respectively, where $k$ is a positive constant. If the measure of $\angle Q$ is $t^{\circ }$, what is the measure of $\angle N$?