B) $$rac{6x^2 + 12xy}{5xy + 10y^2}$$ при $$x = \frac{2}{3}$$, $$y = -0,4$$;

B) $$\frac{6x^2 + 12xy}{5xy + 10y^2} = \frac{6x(x + 2y)}{5y(x + 2y)} = \frac{6x}{5y}$$

Подставим значения $$x = \frac{2}{3}$$, $$y = -0,4$$:

$$\frac{6 \cdot \frac{2}{3}}{5 \cdot (-0,4)} = \frac{4}{-2} = -2$$

Ответ: -2