Tìm số hữu tỉ x, biết

a)$ x + (-\frac{2}{5}) = \frac{-1}{3}$

$ x = \frac{-1}{3} - (-\frac{2}{5})$

$x = \frac{1}{15}$.

b) $0.5 - x = \frac{-5}{14}$

$x = 0.5 - \frac{-5}{14}$

$x = \frac{6}{7}$

c) $(-0.4) \times (2x + \frac{2}{5}) = -9.4$

$2x = [-9.4 / (-0.4)] - \frac{2}{5}$

$2x = \frac{231}{10}$

$x = \frac{231}{20}$

d)$ (\frac{3}{2} - x) / \frac{-14}{3} = \frac{-6}{7}.$

$ \frac{3}{2} - x = \frac{-6}{7} \times \frac{-14}{3} $

$ \frac{3}{2} - x = 4$

$x = \frac{3}{2} - 4 = \frac{-5}{2}$