First we need to determine the circumference of the bath.
Circumference = Diameter X pi
6(pi) = 18.84 feet
and the girls want to put perches that are at least 3 feet between each other so you can just divide the circumference by 3
18.84 / 3 = 6.28 so 6
If you don't understand the concept then think of it like this, if you have in total 18.84 feet and you want to place something down every 3 feet then start subtracting 3 from your total till you can't add anymore perches.
18 - 3 = 15
15 - 3 = 12
12 - 3 = 9
9 - 3 = 6
6 - 3 = 3
3 - 3 = 0
We subtracted 3, SIX times so we added 6 perches
