14. 11 +13

14. $$11 \frac{6}{7} + 13 \frac{5}{7} = (11+13) + (\frac{6}{7} + \frac{5}{7}) = 24 + \frac{11}{7} = 24 + 1 \frac{4}{7} = 25 \frac{4}{7}$$

Ответ: $$25 \frac{4}{7}$$