21) 9

If you are not sure about solving powers, click here.

Let us solve the values given in the problem individually.

32^¹⁄₅ = ⁵√32 = 2

9⁰ = 1

81^¾ = (⁴√81)³
⁴√81 = 3
(⁴√81)³ = (3)³ = 27

So we have:
²⁺¹⁄₂₇ = ³⁄₂₇ = ¹⁄₉

We also have a (⁻¹) power too.
So (¹⁄₉)⁻¹ = 9