д) $$\frac{35}{39} \cdot \frac{13}{42} - \frac{1}{6}$$

д) $$\frac{35}{39} \cdot \frac{13}{42} - \frac{1}{6} = \frac{35 \cdot 13}{39 \cdot 42} - \frac{1}{6} = \frac{5 \cdot 1}{3 \cdot 6} - \frac{1}{6} = \frac{5}{18} - \frac{1}{6} = \frac{5}{18} - \frac{1 \cdot 3}{6 \cdot 3} = \frac{5}{18} - \frac{3}{18} = \frac{2}{18} = \frac{1}{9}$$

Ответ: $$\frac{1}{9}$$