Найдите значение выражения: a) $$2\frac{3}{4} - 1\frac{5}{6}$$; б) $$4\frac{2}{5} + 3\frac{5}{6}$$; в) $$7\frac{5}{12} - (1\frac{5}{8} + 2\frac{1}{24})$$.

a) $$2\frac{3}{4} - 1\frac{5}{6} = \frac{11}{4} - \frac{11}{6} = \frac{33}{12} - \frac{22}{12} = \frac{11}{12}$$ б) $$4\frac{2}{5} + 3\frac{5}{6} = \frac{22}{5} + \frac{23}{6} = \frac{132}{30} + \frac{115}{30} = \frac{247}{30} = 8\frac{7}{30}$$ в) $$7\frac{5}{12} - (1\frac{5}{8} + 2\frac{1}{24}) = \frac{89}{12} - (\frac{13}{8} + \frac{49}{24}) = \frac{89}{12} - (\frac{39}{24} + \frac{49}{24}) = \frac{89}{12} - \frac{88}{24} = \frac{178}{24} - \frac{88}{24} = \frac{90}{24} = \frac{15}{4} = 3\frac{3}{4}$$