Your formula is (n-2) x 180 = total
there are 6 angles, so n= 6
(6-2)x 180 = 4 x 180 = 720
Then add all other angles together:
120 + 112 + 100 + 128 + 133 = 593
subtract the other angles to the total amount:
720 (total) - 593 (others) = x
x = 127
your answer is 127 degrees
hope this helps