4.1 > 4.01 > 4.085 > 4.009
I hope this helps! ;D
We know that
In any quadrilateral where the vertices are on the circumference of a circle, the opposite angles add up to

degrees.
So,
in this problem

therefore
the answer is
2n+5...a couple is two people so you need to multiply the number of couples, n, by 2 to get the total number of dancers. Then add the total number of organizers.