Using
(n-2)180 = 18001800
(n-2) = 18001800÷180
n-2 = 100010
n = 100010+2
n= 100012 sides
I don't either it is quite hard to be fair

Hope that helps and hope you get better!
What is the context for the question if there is any?
100 + 8d = 300; d = 25; The kitten will triple its weight in 25 days