Since we can see that the line on the top, the one across the yellow box, is the main one, and that one measures 180*, so that means that we have to justsubtract 180 by 71, and that will be our answer!
180-71 =109
So, the angle of the missing angle is 109 degrees.
Another proof that this is your answer is that 109 degrees is obtuse, and we can easily say that the angle here is also obtuse.
