Verified Answer :

((-4)^5)^8 / ((-4)^7)^3

= (-4)^40 / (-4)^21

= (-4)^20

so you need to simplify the two fractions by first simplifying the exponent. this would mean that each deviant has one set of exponent instead of a pair.
thus, -440 ÷ -421
the two bases are equal.
#4 rule states that when an/bm (fraction). if bases are the same, the exponent of the denominator is subtracted to the exponent of the numerator. assuming a & b are equal, the answer will look like this: (a(n-m))
so apply this rule to your question. also, it'll be helpful to learn the laws of indices.

final answer: 4
19
NOTE: stands for 'the power of
so in word form your answer is four to the power of nineteen.

Hope this helped :)