Explanation:
Let the unnamed angle in the triangle be x.
x + 136 = 180 (Sum of angles on the same straight line)
x = 180 - 136
= 44
Angle 1 + x + 33 = 180 (Sum of angles in a triangle)
Angle 1 + 44 + 33 = 180
Angle 1 + 77 = 180
Angle 1 = 180 - 77
= 103