$(\frac{4a^2b}{a^3b^2}):($$\frac{2b^4}{5a^2b})$
źródło:
\frac{4a^2b}{a^3b^2}*\frac{5a^2b}{2b^4}=\frac{20a^4b^2}{2a^3b^6}=\frac{10a}{b^4}=10ab^{-4}