$\widehat{yOz}=120^{\circ}-70^{\circ}=50^{\circ};$
$\widehat{xOm}=70^{\circ}/2=35^{\circ};$
$\widehat{xOn}=120^{\circ}/2=60^{\circ};$
$\widehat{mOn}=70^{\circ}-35^{\circ}-(70^{\circ}-60^{\circ})=25^{\circ}$
$\widehat{yOz}=120^{\circ}-70^{\circ}=50^{\circ};$
$\widehat{xOm}=70^{\circ}/2=35^{\circ};$
$\widehat{xOn}=120^{\circ}/2=60^{\circ};$
$\widehat{mOn}=70^{\circ}-35^{\circ}-(70^{\circ}-60^{\circ})=25^{\circ}$