$\frac{{\left(a^{-2}\right)}^{-4}\cdot {\left(a^5:a^{-4}\right)}^{-2}}{{\left(a^{12}\right)}^{-1}}$ $=\frac{a^{-2\left(-4\right)}\cdot {\left(a^{5-\left(-4\right)}\right)}^{-2}}{a^{12\cdot \left(-1\right)}}$ $=\frac{a^8\cdot {\left(a^9\right)}^{-2}}{a^{-12}}=$ $\frac{a^8\cdot {\left(a^9\right)}^{-2}}{a^{-12}}$ $=\frac{a^8\cdot a^{-18}}{a^{-12}}=\frac{a^{8+\left(-18\right)}}{a^{-12}}=$

$=\frac{a^{-10}}{a^{-12}}=a^{-10-\left(-12\right)}=a^2$

$\frac{{\left(x^{-3}:x^{-2}\right)}^{-3}}{{\left(\frac{1}{x}\right)}^{-2}\cdot x^{-3}:x^{-2}}=$ $\frac{{\left(x^{-3-\left(-2\right)}\right)}^{-3}}{x^2\cdot x^{-3}:x^{-2}}=$ $\frac{{\left(x^{-1}\right)}^{-3}}{x^{2+\left(-3\right)-\left(-2\right)}}=$ $\frac{x^{-1\cdot \left(-3\right)}}{x}=x^{3-1}=x^2$