We have the following expression given:
[tex]\frac{5^{-4}}{5^3}[/tex]For this case since we have the same base 5 we can apply the following rule:
[tex]\frac{a^x}{a^y}=a^{x-y}[/tex]And using this rule we have:
[tex]\frac{5^{-4}}{5^3}=5^{-4-3}=5^{-7}[/tex]And the best answer for this case would be:
[tex]5^{-7}=\frac{1}{5^7}[/tex]