How do you rewrite y^-5 using a positive exponent?

${\left(\frac{1}{y}\right)}^{5}$
So, ${y}^{- 5} = \frac{1}{{y}^{5}}$, and since ${1}^{5} = 1$, we can write $\frac{1}{{y}^{5}}$ as ${1}^{5} / \left\{{y}^{5}\right\}$, and thus ${\left(\frac{1}{y}\right)}^{5}$.