({x^-1 y^4 z^-4}{y^-2 z^3 x^-5})^-1 =z^r/(x^s y^t)

r the exponent of z is

s the exponent of x is

t the exponent of y is

Just remember that

x^{a}x^{b} = x^{a+b}

and these rules apply to the power expressions as well.

also

(a/b)^{-c} = (b/a)^{c} might help.