[tex]
a)-\frac{4a}{5c^2}:(-\frac{a}{10c^4})=-\frac{4a}{5c^2}\cdot(-\frac{10c^4}{a})=8
б)\frac{m^2-4n^2}{m^2}:(4m-8n)=\frac{m^2-4n^2}{m^2}\cdot\frac{1}{4m-8n}=\frac{m+2n}{4m^2}
в)\frac{2x-1}{x^2-6x+9}:\frac{1-2x}{x^2-3x}=\frac{2x-1}{x^2-6x+9}\cdot\frac{x^2-3x}{1-2x}=-\frac{x}{x-3}
г)\frac{2a-4}{a^2+4}:\frac{a^2-4a+4}{a^4-16}=\frac{2a-4}{a^2+4}\cdot\frac{a^3-16}{a^2-4a+4}=\frac{2a^2-8}{a-2}[tex]