Answer:
a^ 8 / b^12
Step-by-step explanation:
We know that x^y / x^z = x^ (y-z)
a^-5 b^-4
----------------
a^ -13 b^8
a^ (-5 - -13) b ^ (-4 -8)
a^ (-5+13) b^ (-4-8)
a^ 8 b^ (-12)
We know that x ^ - y = 1/ x^y
