3) a) 2(x-y); ; 6) 3c-9d x(y-x)' 6d-2c'

3) a) $$ \frac{2(x-y)}{x(y-x)} = -\frac{2(y-x)}{x(y-x)} = -\frac{2}{x} $$

б) $$ \frac{3c-9d}{6d-2c} = \frac{3(c-3d)}{-2(c-3d)} = -\frac{3}{2} $$

Ответ: a) $$\- \frac{2}{x}$$; б) $$\- \frac{3}{2}$$