A) $$ \frac{4}{7} + \frac{2}{7} = \frac{4+2}{7} = \frac{6}{7} $$
Б) $$ \frac{8}{11} + \frac{7}{11} = \frac{8+7}{11} = \frac{15}{11} = 1\frac{4}{11} $$
В) $$ 4\frac{7}{11} + 8\frac{9}{11} = (4 + 8) + (\frac{7}{11} + \frac{9}{11}) = 12 + \frac{16}{11} = 12 + 1\frac{5}{11} = 13\frac{5}{11} $$
Г) $$ 9\frac{10}{13} - 7\frac{12}{13} = (9 - 7) + (\frac{10}{13} - \frac{12}{13}) = 2 - \frac{2}{13} = 1\frac{13}{13} - \frac{2}{13} = 1\frac{11}{13} $$
Д) $$ \frac{1}{2} + \frac{1}{3} = \frac{1*3}{2*3} + \frac{1*2}{3*2} = \frac{3}{6} + \frac{2}{6} = \frac{3+2}{6} = \frac{5}{6} $$
Ответ: А) $$ \frac{6}{7} $$; Б) $$ 1\frac{4}{11} $$; В) $$ 13\frac{5}{11} $$; Г) $$ 1\frac{11}{13} $$; Д) $$ \frac{5}{6} $$