Сократи: 8/14, 7/63, 30/84, (34 · 12)/(3 · 17).

\(\frac{8}{14}=\frac{4}{7}\); \(\frac{7}{63}=\frac{1}{9}\); \(\frac{30}{84}=\frac{5}{14}\); \(\frac{34\cdot12}{3\cdot17}=\frac{2\cdot12}{3}=8\).

Ответ: \(\frac{4}{7};\ \frac{1}{9};\ \frac{5}{14};\ 8\).