Simplify:
$\displaystyle{(-4a^{-2}b^4)^2(-a^2b^{-4}c)^3(ab^{-3}c^4)^2}$
$\displaystyle{\frac{18xy^3z^{-5}}{27x^{-2}y^2z^2}}$
$\displaystyle{\left[ \frac{-5x^{-3}}{(16y^2)^{-1/2}} \right]^{-1}}$
$\displaystyle{(3x^2y^3)(-2x^{-3}y^2)(xy^2z^{1/3})^0}$
$\displaystyle{(a+b)^{2/3}(a+b)}$
$\displaystyle{\frac{(3x^{-1/2}y^{2/3})^{-2}}{(xy^{-1})^{-3}}}$
$\displaystyle{(7a^2 b^4)(-2a^{-4} b^3)}$
$\displaystyle{(4x^4 y^{-2})(-3x^5 y^{-4})}$
$\displaystyle{\frac{24pq^8 r^{-4}}{36 p^{-3} q^{-6} r^5}}$
$\displaystyle{\frac{54 x^6 y^{-4} z^2}{9x^{-3} y^2 z^{-4}}}$
$\displaystyle{\left( \frac{25a^6 b^{-2}}{16x^4 a^4} \right)^{-\frac{1}{2}}}$
$\displaystyle{\left( \frac{25xy^{-2}}{16a^4b^6} \right)^{-\frac{1}{2}}}$
$\displaystyle{\frac{(2k^2 rt)^{-2}}{(3k^{-1} r^{-2} t^3 )^{-1}}}$
$\displaystyle{\left( \frac{27x^2}{w^6} \right)^{-\frac{1}{3}}}$
$\displaystyle{y^3 \cdot \left( \frac{45x^{-2} y^3 (zw^{-1})^0}{(-3)^3 x^{-4} y^{-2} w z^3} \right)^{-2}}$
$\displaystyle{\left( \frac{16^{-1/4} + (-4)^{-2} - 2^{-3}}{8^{1/3}} \right)^{-1}}$