(a^5 B/a^7 B^-2)^-3

Answer 1

(a^5 B/a^7 B^-2)^-3
again, you probably meant:
(a^5 b/(a^7 b^-2))^-3 , (any reason for the capital B ?)
= [(b^3)/a^2)]^-3
= [a^2/b^3]^3
= a^6/b^9