10 is 20 degrees
11 is 180-145= 35 degrees
12, so the way you do it is by the fact that one opposite exterior angle is equal to two interior angles, so 40+46= 86 degrees.
8 is 86-35= 51 degrees
9 is 29 plus 62 equals 91 degrees.
Hope this helps! I tried to type this really fast
