Find the value of ${\left(-\frac{1}{2}\right)}^{-1}$.

Find the value of $7^0+8^0+9^0$.

Find the value of $\left({20}^0-{23}^0\right)\times {18}^0$.

Find the value of $3^0\times 3^{-1}$.

Find the value of $2^{-1}\times 2^{-3}$.

Find the value of ${\left(3^{-1}÷4^{-1}\right)}^2$. (Give answer as improper fraction)

Find the value of $\left(4^{-1}+8^{-1}\right)÷{\left(\frac{2}{3}\right)}^{-1}$.

Simplify: ${\left(\frac{2}{3}\right)}^{-2}\times {\left(\frac{3}{4}\right)}^{-3}\times {\left(\frac{7}{8}\right)}^0$. (Give answer as improper fraction)

Simplify: ${\left(\frac{4}{9}\right)}^{-2}\times {\left(\frac{1}{4}\right)}^{-2}\times \frac{1}{3^{-2}}\times {\left(\frac{17}{18}\right)}^0$