Your answer is C. 137°
To find the answer, you first need to find the missing angle in the triangle, which you can do by adding 103 and 34 to make 137°, and then subtracting that from 180° to find 43°.
Because angles on a straight line add up to 180°, you now again need to do 180 - 43 = 137°, which is your answer.
I hope this helps!
