As can be seen from the picture, there are always two people on each side of the inner floor than the outer floor.
The formula for calculating the number of people on each floor is: (number of people on each side-1)×4.
The equation can be obtained: 4× (x-1)+4× (x-3)+4× (x-5) =180.
Solution: x= 18
A: There are 18 people on both sides of the outermost layer.