56. \(\frac{13}{14}\) : \(\frac{7}{26}\) : \(\frac{3}{8}\)

1. First division: $$\frac{13}{14} : \frac{7}{26} = \frac{13}{14} \cdot \frac{26}{7} = \frac{13 \cdot 13}{7 \cdot 7} = \frac{169}{49}$$.
2. Second division: $$\frac{169}{49} : \frac{3}{8} = \frac{169}{49} \cdot \frac{8}{3} = \frac{1352}{147}$$.
3. Convert to mixed number: $$\frac{1352}{147} = 9 \frac{29}{147}$$.