Question

What is the measure of ∠O in this quadrilateral?

Answer 1

Since you know 
a) there are 360 degrees in a quadrilateral
b) the values of angles M, N, and L
You can subtract all 3 of those angles from 360 to get the answer.

360-112-63-63 = 122 degrees.
angle O is 122 degrees.

Hope this helped you some. :)