STILL DON'T GET THIS can anyone explain me this please a cylinder has a volume of 19cm^3. If the radius is doubled, what is the volume of the new cylinder? HOW TO DO THIS

let the original radius be r , and the height be h

πr^2 h = V
π r^2 h = 19

new radius = 2r

new Volume
= π(2r)^2 h
= π(4r^2) h = 4 (πr^2 h) = 4(19) = 76