Solutions
angle N = 120
0 ........(180-60=120, Sum of straight angle)

In the above figure,
angle MNX = angle OXN= 60
0 ............(alternate angles)
also, angle MNX = angle ONX ........(angle bisector)
therefore ΔOXN is an isosceles triangle
so, OX = ON
also,
angle XMN = angle MXP= 30
0 ............(alternate angles)
also, angle XMN = angle PMX ........(angle bisector)
therefore ΔPMX is an isosceles triangle
so, PX= PM
As we know that, PM = ON since it is a parallelogram
therefore,
PX= PM= ON = OX
we can write,
OX = PX