Answer
$\frac{a^{20}}{b^{35}}$
Work Step by Step
We know that $a^{−n}=\frac{1}{a^{n}}$ and $\frac{1}{a^{-n}}=a^{n}$ (as long as a is a nonzero real number and n is an integer).
Therefore, $(a^{-4}b^{7})^{-5}=(a^{-4})^{-5}(b^{7})^{-5}=a^{-4\times-5}b^{7\times-5}=a^{20}b^{-35}=a^{20}\times\frac{1}{b^{35}}=\frac{a^{20}}{b^{35}}$.
