1. Вычислите: a) $$\frac{3}{4} + \frac{1}{11}$$; б) $$\frac{3}{8} \cdot \frac{2}{5}$$; в) $$2 - \frac{5}{6} : \frac{8}{9}$$

a) $$\frac{3}{4} + \frac{1}{11} = \frac{3 \cdot 11}{4 \cdot 11} + \frac{1 \cdot 4}{11 \cdot 4} = \frac{33}{44} + \frac{4}{44} = \frac{33+4}{44} = \frac{37}{44}$$ б) $$\frac{3}{8} \cdot \frac{2}{5} = \frac{3 \cdot 2}{8 \cdot 5} = \frac{6}{40} = \frac{3}{20}$$ в) $$2 - \frac{5}{6} : \frac{8}{9} = 2 - \frac{5}{6} \cdot \frac{9}{8} = 2 - \frac{5 \cdot 9}{6 \cdot 8} = 2 - \frac{45}{48} = 2 - \frac{15}{16} = \frac{2 \cdot 16}{16} - \frac{15}{16} = \frac{32}{16} - \frac{15}{16} = \frac{32-15}{16} = \frac{17}{16} = 1\frac{1}{16}$$ Ответ: a) $$\frac{37}{44}$$ б) $$\frac{3}{20}$$ в) $$1\frac{1}{16}$$