4. Решите уравнение: 1) -8x = 72; 2) x : (-2,7) = -5,4. 3)1/9 : x = -8/27 4) -3 4/7 x = 25/28

1) $$-8x = 72$$ $$x = \frac{72}{-8}$$ $$x = -9$$ 2) $$x : (-2,7) = -5,4$$ $$x = -5,4 \cdot (-2,7)$$ $$x = 14,58$$ 3) $$\frac{1}{9} : x = -\frac{8}{27}$$ $$\frac{1}{9x} = -\frac{8}{27}$$ $$-8x = \frac{27}{9}$$ $$-8x = 3$$ $$x = -\frac{3}{8} = -0,375$$ 4) $$-3\frac{4}{7} x = \frac{25}{28}$$ $$-\frac{25}{7} x = \frac{25}{28}$$ $$x = \frac{25}{28} : \left(-\frac{25}{7}\right)$$ $$x = \frac{25}{28} \cdot \left(-\frac{7}{25}\right)$$ $$x = -\frac{1}{4} = -0,25$$