Answer
$\frac{49}{36}$
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, $(\frac{6}{7})^{-2}=\frac{1}{6^{2}}\times7^{2}=\frac{49}{36}$.