50.13.7.3

50. $$ \frac{13}{14} : \frac{7}{26} : \frac{3}{8} = \frac{13}{14} \cdot \frac{26}{7} \cdot \frac{8}{3} = \frac{13 \cdot 26 \cdot 8}{14 \cdot 7 \cdot 3} = \frac{13 \cdot 13 \cdot 8}{7 \cdot 7 \cdot 3} = \frac{1352}{147} = 9\frac{29}{147}$$

Ответ: $$9\frac{29}{147}$$