Given:
[tex]\angle PRO=23[/tex]
Any tengent make the angle with the circle radius is 90 degree.
That mean:
[tex]\angle OPR=90[/tex]
Sum of all angle of triangle is 180 degree.
[tex]\begin{gathered} \angle POR+\angle PRO+\angle OPR=180 \\ \angle POR+23+90=180 \\ \angle POR=180-(90+23) \\ \angle POR=180-113 \\ \angle POR=67 \end{gathered}[/tex]
