Answer: 5^-13
Explanation:
You can first convert the division to a multiplication :
Dividing by 5^8 is the same as multiplying by the inverse, so :
5^-5 / 5^8 = 5^-5 * 1/5^8
You can rewrite 1/5^8 as 5^-8
so 5^-5 * 1/5^8 = 5^-5 * 5^-8
you then just need to add the exponents in a multiplication
5^-5 * 5^-8 = 5^(-5-8) = 5^-13