Can someone explain this exponential expression problem to me please?

(3x/y^3)^-3
So I got the answer (1/27x^3)/ 1/x^9.
Is this correct and if not where did I go wrong?

What happened to your y's? Typo, I'd guess

So far, so good:

(1/27x^3)/ (1/y^9)
= (1/27x^3) * y^9
= y^9/27x^3

Or, you could have done

(3x/y^3)^-3
= (y^3/3x)^3
= y^9/27x^3