Find the value of ${\left(\frac{1}{3}\right)}^{-1}+{\left(\frac{1}{5}\right)}^{-1}-{\left(\frac{1}{6}\right)}^{-1}$.

Simplify ${\left(\frac{2}{3}\right)}^{-2}\times {\left(-\frac{7}{8}\right)}^0$.

If $\frac{a}{b}={\left(\frac{2}{3}\right)}^{-3}\times {\left(\frac{5}{6}\right)}^0$, find the value of ${\left(\frac{a}{b}\right)}^{-3}$.

Find the value of $x$, if ${\left(\frac{5}{6}\right)}^7\times {\left(\frac{5}{6}\right)}^{-9}={\left(\frac{5}{6}\right)}^{2x}$.

Find the value of $3^{-4}$.

Find the value: ${\left[{\left(-2\right)}^{-1}\right]}^{-1}$

Express $0.000543$ in scientific notation.

If $\frac{x^{-2}}{x^n}=\frac{1}{x^{12}}$, find the value of $n$.