Explanation:
Hi, there!!!
It's so simple..
Let me clear you, alright.
Here, On the fig line, OE is just a confusing line. If you look it in simple way,
AB and CD are interested at a point O.
so, angle AOD and angle COB are equal.{ because they are vertically opposite angle}
so, angle AOD= angle COB
or, 4x°=45°+15°
or, 4x°= 60°
or, x= 60°/4
Therefore, x= 15°.
Hope it helps....