3. Выполнить действия: а) $$18-13\frac{4}{7}$$; б) $$6\frac{5}{6}+3\frac{5}{12}$$; в) $$2\frac{4}{9} \cdot 2\frac{1}{22}$$; г) $$2\frac{11}{12}:5\frac{5}{6}$$.

а) $$18-13\frac{4}{7} = 17\frac{7}{7}-13\frac{4}{7} = (17-13) + (\frac{7}{7}-\frac{4}{7}) = 4\frac{3}{7}$$. б) $$6\frac{5}{6}+3\frac{5}{12} = 6\frac{10}{12}+3\frac{5}{12} = (6+3) + (\frac{10}{12}+\frac{5}{12}) = 9 + \frac{15}{12} = 9 + 1\frac{3}{12} = 10\frac{3}{12} = 10\frac{1}{4}$$. в) $$2\frac{4}{9} \cdot 2\frac{1}{22} = \frac{22}{9} \cdot \frac{45}{22} = \frac{22 \cdot 45}{9 \cdot 22} = \frac{45}{9} = 5$$. г) $$2\frac{11}{12}:5\frac{5}{6} = \frac{35}{12}:\frac{35}{6} = \frac{35}{12} \cdot \frac{6}{35} = \frac{35 \cdot 6}{12 \cdot 35} = \frac{6}{12} = \frac{1}{2}$$.