A parallel line is something that is equivalent on the other end. This mean if you cut a shape, a square for example, in half,the sides will be of equal length.
The formula is 180(n-2)= 1140 then you divide 1140 by 180 to get 8 so then it would like like n-2=8 add the 2 over and n (being the number of sides)= 10 so your answer will be 10
