a) $$\frac{19}{30} - x = \frac{14}{30} - \frac{3}{30}$$
$$\frac{19}{30} - x = \frac{11}{30}$$
$$x = \frac{19}{30} - \frac{11}{30}$$
$$x = \frac{8}{30} = \frac{4}{15}$$
Ответ: $$\frac{4}{15}$$