[(z^n)^3] / [z^n*z^3]

Question

How can I set this up? I'm pretty sure you have to simplify so that it's z^3n / z^n+3 but where can I do from there? or am I messing up a step somewhere?

(z^n)^3= z^3n
and
z^n * Z^3= Z^(n+3)

so z^3n / Z^(n+3) = z^(3n-n+3)