SMO 2009 Junior Round 1 Question 26

In the diagram, $OAB$ is a triangle with $\angle AOB=90^\circ$ and $OB=13$ cm. $P$ and $Q$ are two points on $AB$ such that $26AP=22PQ=11QB$. If the vertical height of $PQ$ is $4$ cm, find the area of triangle $OPQ$ in $\text{cm}^2$.