How to find the length of a cylinder when u have volume and circumference

Circumfernce=2pir
Vcylinder=lpir^2

so what you do is take circumference adnd solvefor r, then input that for r in Volume and solve for legnth

C=2pir
C/(2pi)=r
input
V=lpir^2
V=lpi(C/2pi)^2
V=lpi(c^2/(4pi^2))
V=l(c^2/4pi)
multiply both sides by (4pi)/(c^2) to clear fractio
(4piV)/(C^2)=legnth

basically if  you know volume and circumference
legnth=(4pi tmes volume)/(circumference^2)

Add them all together then u will get your answer