The 3 inside angles of a triangle need to equal 180 degrees.
You are told two of the angles are 106 and 59.
To find the 3rd angle subtract the 2 known angles from 180:
180 - 106 - 59 = 15 degrees.
The one on the left side: 180 - 33 - 114 = 33
The one on the right: 180 - 90 - 73 = 17