In trapezoid $PQRS$, $\overline{PS}$ is perpendicular to $\overline{SR}$, $PS=4$, $PQ=5$, and $SR=9$. In addition, $T$ is on $\overline{SR}$, and $\overline{QT}$ is parallel to $\overline{PS}$. Find the area of $△QTR$.