[tex]Use:\\\dfrac{a^n}{a^m}=a^{n-m}\\\\(a^n)^m=a^{n\cdot m}\\\\(a\cdot b)^n=a^n\cdot b^n[/tex]
[tex]
\left(\dfrac{xy^2}{x^{-3}y^3}\right)^{-4}=\left(x^{1-(-3)}y^{2-3}\right)^{-4}=\left(x^4y^{-1}\right)^{-4}\\\\x^{4\cdot(-4)}y^{-1\cdot(-4)}=\boxed{x^{-16}y^4}=\boxed{\frac{y^4}{x^{16}}}[/tex]
