Решим пример:
$$11\frac{6}{13}-9\frac{4}{13} = \frac{149}{13}-\frac{121}{13} = \frac{149-121}{13} = \frac{28}{13} = 2\frac{2}{13}$$
Решим пример:
$$12\frac{15}{19}-8\frac{13}{19} = \frac{243}{19} - \frac{165}{19} = \frac{243-165}{19} = \frac{78}{19} = 4\frac{2}{19}$$
Ответ: 8) $$2\frac{2}{13}$$; 9) $$4\frac{2}{19}$$