19) $$\frac{10}{x^2} \cdot \frac{6x}{25} \cdot \frac{x}{9} =$$

$$\frac{10}{x^2} \cdot \frac{6x}{25} \cdot \frac{x}{9} = \frac{10 \cdot 6x \cdot x}{x^2 \cdot 25 \cdot 9} = \frac{60x^2}{225x^2} = \frac{60}{225} = \frac{4}{15}$$ Ответ: $$\frac{4}{15}$$