a hexagon has 6 sides An octagon has 8 sides.
Hope i helped <3
7a)

If n is the amount of sides then there's 38 sides in a polygon with 665 diagonals
7b)
We do the same as 7a) but with 406. We get that
and
. A polygon cant have 30.04 sides
It goes into 5 times hope you enjoy
5+2
3+4
6+1
any one of these answers is good