How do you express (-3)^-3 as a positive exponent?

Use this rule for exponents: ${x}^{\textcolor{red}{a}} = \frac{1}{x} ^ \textcolor{red}{- a}$
${\left(- 3\right)}^{\textcolor{red}{- 3}} = \frac{1}{- {3}^{\textcolor{red}{- - 3}}} = \frac{1}{- {3}^{\textcolor{red}{3}}}$