270. Найдите неизвестный член пропорции: a) $$\frac{x}{-2,3} = \frac{-5,8}{-4,6}$$; б) $$\frac{-2,8}{35} = \frac{-4,2}{x}$$; в) $$\frac{-2\frac{2}{9}}{x} = \frac{11\frac{2}{3}}{-1\frac{2}{5}}$$; г) $$\frac{-\frac{2}{7}}{\frac{3}{14}} = \frac{x}{\frac{5}{6}}$$.

a) $$\frac{x}{-2,3} = \frac{-5,8}{-4,6}$$ $$x = \frac{(-2,3) \cdot (-5,8)}{-4,6}$$ $$x = \frac{13,34}{-4,6}$$ $$x = -2,9$$ б) $$\frac{-2,8}{35} = \frac{-4,2}{x}$$ $$x = \frac{35 \cdot (-4,2)}{-2,8}$$ $$x = \frac{-147}{-2,8}$$ $$x = 52,5$$ в) $$\frac{-2\frac{2}{9}}{x} = \frac{11\frac{2}{3}}{-1\frac{2}{5}}$$ $$\frac{-\frac{20}{9}}{x} = \frac{\frac{35}{3}}{-\frac{7}{5}}$$ $$x = \frac{-\frac{20}{9} \cdot (-\frac{7}{5})}{\frac{35}{3}}$$ $$x = \frac{\frac{28}{9}}{\frac{35}{3}}$$ $$x = \frac{28}{9} \cdot \frac{3}{35}$$ $$x = \frac{4}{3} \cdot \frac{1}{5}$$ $$x = \frac{4}{15}$$ г) $$\frac{-\frac{2}{7}}{\frac{3}{14}} = \frac{x}{\frac{5}{6}}$$ $$x = \frac{-\frac{2}{7} \cdot \frac{5}{6}}{\frac{3}{14}}$$ $$x = \frac{-\frac{5}{21}}{\frac{3}{14}}$$ $$x = -\frac{5}{21} \cdot \frac{14}{3}$$ $$x = -\frac{5}{3} \cdot \frac{2}{3}$$ $$x = -\frac{10}{9}$$ $$x = -1\frac{1}{9}$$