3^{(5 − 10)}

$3^{-5}=\frac{1}{3^{5}}$

Remember, when an exponent is located outside of a group of parentheses, the exponent applies to each and every value within the parentheses.

$10x^{4}\left(10^{−2}x^{−2}\right)$

$\frac{{\it x}^{2}}{10}$

This can be rewritten as:

$\left(4^{−1}\right)^{3}\left(4\right)^{2}$

See (b).

See (a) and (b).