\[Схематический\ рисунок.\]
\[\angle MOK = 172{^\circ};\angle POK = 85:\]
\[\angle MOK = \angle MOP + \angle POK\]
\[172{^\circ} = \angle MOP + 85{^\circ}\]
\[\angle MOP = 87{^\circ}.\]
\[Ответ:\ \ 87{^\circ}.\]