A negative exponent just means that the base is on the wrong side of the fraction line, so you need to flip the base to the other side.
For example
[tex]x^{-2}=\frac{1}{x^2}[/tex]
or
[tex]( \frac{2}{5} )^{-4}=( \frac{5}{2} )^4[/tex]
***************************************
[tex](8r^{-5})^{-3}[/tex]
[tex](8* \frac{1}{r^5} )^{-3} \\\\( \frac{8}{r^5} )^{-3}
\\ \\ ( \frac{r^5}{8} )^3
\\\\ \mathrm{Apply\:exponent\:rule}:\quad *\left(\frac{a}{b}\right)^c=\frac{a^c}{b^c} \ \ \ \ \ \ \ \ \ \ \ \ *(a^b)^c=a^{bc}
\\\\( \frac{r^{15}}{8^3} )
\\\\( \frac{r^{15}}{512} )[/tex]
The answer is "D"
