Answer
a) Exponents, when dividing powers with the same base, can be subtracted.
b) Answers may vary. One example: $\frac{a^4}{a^8} = \frac{1}{a^4}$
Work Step by Step
a) The property used is that $\frac{a^m}{a^n} = a^{m-n}$ when $m$ and $n$ are integers and $a \ne0$. However, when $n > m$, we will have $\frac{1}{a^{n-m}}$.
b)
$\frac{a^4}{a^8} = \frac{1}{a^{8-4}} = \frac{1}{a^4}$
