4. Найди значение выражения \(\frac{14}{15}:x\) при \(x=\frac{2}{5};\ \frac{2}{3};\ \frac{7}{30};\ \frac{4}{5}\).

1. При \(x=\frac{2}{5}\): \(\frac{14}{15}:\frac{2}{5}=\frac{14}{15}\cdot\frac{5}{2}=\frac{7}{3}\).
2. При \(x=\frac{2}{3}\): \(\frac{14}{15}:\frac{2}{3}=\frac{14}{15}\cdot\frac{3}{2}=\frac{7}{5}\).
3. При \(x=\frac{7}{30}\): \(\frac{14}{15}:\frac{7}{30}=\frac{14}{15}\cdot\frac{30}{7}=4\).
4. При \(x=\frac{4}{5}\): \(\frac{14}{15}:\frac{4}{5}=\frac{14}{15}\cdot\frac{5}{4}=\frac{7}{6}\).

Ответ: \(\frac{7}{3};\ \frac{7}{5};\ 4;\ \frac{7}{6}\).