13 2+(-1)

Решим пример:

$$\begin{aligned}
2\frac{1}{6} : \frac{3}{7} + \left(4 - 1\frac{3}{8}\right) = \frac{13}{6} \cdot \frac{7}{3} + \left(\frac{4}{1} - \frac{11}{8}\right) = \frac{91}{18} + \frac{32 - 11}{8} = \frac{91}{18} + \frac{21}{8} = \frac{91 \cdot 4 + 21 \cdot 9}{72} = \frac{364 + 189}{72} = \frac{553}{72} = 7\frac{49}{72}
\end{aligned}$$

Ответ: $$7\frac{49}{72}$$