Answer :
Those are vertical angles, therefore:
[tex]\begin{gathered} m\angle ONB=m\angle MNK \\ so\colon \\ m\angle ONB=85 \end{gathered}[/tex]Those are vertical angles, therefore:
[tex]\begin{gathered} m\angle ONB=m\angle MNK \\ so\colon \\ m\angle ONB=85 \end{gathered}[/tex]