a) $$\frac{9}{10} - \frac{1}{10} = \frac{9-1}{10} = \frac{8}{10} = \frac{4}{5}$$
Ответ: $$\frac{4}{5}$$
б) $$\frac{8}{15} + \frac{2}{15} = \frac{8+2}{15} = \frac{10}{15} = \frac{2}{3}$$
Ответ: $$\frac{2}{3}$$
г) $$\frac{4}{8} + \frac{2}{8} = \frac{4+2}{8} = \frac{6}{8} = \frac{3}{4}$$
Ответ: $$\frac{3}{4}$$
e) $$\frac{1}{9} + \frac{5}{9} = \frac{1+5}{9} = \frac{6}{9} = \frac{2}{3}$$
Ответ: $$\frac{2}{3}$$