I can't speak to the cactus specifically, but any sphere has a surface area of

and a volume of

, so the area-to-volume ratio wold be


Where <em>r</em> is the radius of the sphere.
Number of angles = number of sides
180 - 120 = 60 (calculating the exterior angle)
360 / 60 = 6
There are 6 sides.
Hope this helps! :)
X + (x + 2) + ( x + 4) + (x + 6)
----------------------------------- = 15
4
4x + 12
--------- = 15
4
Multiply by 4 on both sides
4x + 12 = 60
subtract 12 from both sides
4x = 48
divide by 4 on each side
x = 12
x + 2 = 14
x + 4 = 16
x + 6 = 18
The slope in short is:
4/7