Answer:
84
Step-by-step explanation:
I don't really know how to explain it but I'll try my best
Visualize line AB extending past point A (like it does at point B)
You'll see that 180 ( line AB ) minus 129 is 51
Angle 51 is vertical to the other angle inside the triangle that is unnamed.
Now you have 2 angles.
180-45-51=84
