Question 1031755
The total number of degrees in a nine-sided nonagon is found by
180(n-2) = 180(9-2) = 180(7) = 1260 degrees
Since three angles are spoken for already, and they total 147+146+193 = 486, there must be 1260 - 486 = 774 degrees left for the other six angles.
Divide that by six and get
774/6 = 129 degrees each.