Here are the formulas you’ll need:
Surface area: ##2πrh+2πr^2##
Volume: ##πr^2h##
r is the radius of the cylinder and h is its height.
So for example, let’s say you had a cylinder that had a radius of 3 cm and a height of 6 cm. For surface area, you would calculate:
##2π(3)(6)+2π(3)^2##, which will give you ##54π##.
For volume, you would calculate:
##π(3)^2(6)##, which would give you ##54π## as well.
Then you divide the surface area/volume, which here is simply 1.
One note is that the units for surface area would be ##cm^2## whereas for volume they would be ##cm^3##.
Helpful image:
