Answer:
Sum of angles of a polygon with one side less = (12-2)x180 = 1800
Sum of angles of a polygon with one side more = (14-2)x180 = 2160
Step-by-step explanation:
(n-2)x180 = 1980
n = 13
Sum of angles of a polygon with one side less = (12-2)x180 = 1800
Sum of angles of a polygon with one side more = (14-2)x180 = 2160