Answer:

Explanation:
We have the following expression and asked to simplify

Using the exponent rule: x⁻a = 1/xᵃ we get x⁻³ = 1/x³
Using the exponent rule 1/x⁻ᵃ = xᵃ we get 1/z⁻⁴ = z⁴
The resultant expression becomes:

This cannot be simplified any further since the variables are different