2. Найдите значение выражения: a) $$11\frac{3}{20} + 16\frac{3}{40}$$; б) $$6 - 2\frac{10}{13}$$; г) $$4\frac{11}{12} + 5\frac{13}{18}$$; д) $$9\frac{2}{9} - 6\frac{5}{6}$$.

a) $$11\frac{3}{20} + 16\frac{3}{40} = 11\frac{6}{40} + 16\frac{3}{40} = (11+16) + (\frac{6}{40} + \frac{3}{40}) = 27 + \frac{9}{40} = 27\frac{9}{40}$$.

б) $$6 - 2\frac{10}{13} = 5\frac{13}{13} - 2\frac{10}{13} = (5-2) + (\frac{13}{13} - \frac{10}{13}) = 3 + \frac{3}{13} = 3\frac{3}{13}$$.

г) $$4\frac{11}{12} + 5\frac{13}{18} = 4\frac{33}{36} + 5\frac{26}{36} = (4+5) + (\frac{33}{36} + \frac{26}{36}) = 9 + \frac{59}{36} = 9 + 1\frac{23}{36} = 10\frac{23}{36}$$.

д) $$9\frac{2}{9} - 6\frac{5}{6} = 9\frac{4}{18} - 6\frac{15}{18} = 8\frac{22}{18} - 6\frac{15}{18} = (8-6) + (\frac{22}{18} - \frac{15}{18}) = 2 + \frac{7}{18} = 2\frac{7}{18}$$.