$\begin{align}  & \angle OPS=90{}^\circ \{\text{Tangent to a circle }\!\!\}\!\!\text{ } \\ & \angle ORS=90{}^\circ \{\text{Tangent to a circle }\!\!\}\!\!\text{ } \\ & \angle PQR+\angle OPS+\angle ORS+\angle PSR=360{}^\circ  \\ & \{\text{Sum of }\angle s\text{ in quad}\text{. }\!\!\}\!\!\text{ } \\ & m+90{}^\circ +90{}^\circ +70{}^\circ =360{}^\circ  \\ & m=110{}^\circ  \\ & \angle PQR=\tfrac{1}{2}\angle PQR \\ & \{\angle \text{ at circum}\text{.}=2\times \angle \text{ at the centre }\!\!\}\!\!\text{ } \\ & n=\tfrac{1}{2}(110{}^\circ )=55{}^\circ  \\ & m+n=110{}^\circ +55{}^\circ  \\ & m+n=165{}^\circ  \\\end{align}$