how do i do this: (a^2/3)^-1(3a^3/b^5)^-4

I'm assuming that (a^2/3) is a^(2/3)

(a^(2/3)^-1(3a^3/b^5)^-4   .... using ( a^m )^n = a^(m * n)  ...  so we have

a^(-2/3) * [(3)^(-4) * a^(-12) / b^(-20)] =  using a^(-n)  = 1/a^n

b^20 / [a^(2/3) * 3^4 * a^(12)] =

b^20 / [ 81 * a^(12 + 2/3) ] =

b^20 / [ 81 * a^(38/3)]