Выполните действия: a) $$rac{1}{6} + \frac{3}{7}$$; б) $$6\frac{3}{8} + 16\frac{7}{16}$$; в) $$rac{6}{25} \cdot \frac{5}{18}$$; г) $$\frac{5}{9} : \frac{10}{27}$$

a) $$\frac{1}{6} + \frac{3}{7} = \frac{1 \cdot 7 + 3 \cdot 6}{6 \cdot 7} = \frac{7+18}{42} = \frac{25}{42}$$ б) $$6\frac{3}{8} + 16\frac{7}{16} = 6 + \frac{3}{8} + 16 + \frac{7}{16} = (6+16) + (\frac{3}{8} + \frac{7}{16}) = 22 + (\frac{3 \cdot 2 + 7}{16}) = 22 + \frac{6+7}{16} = 22 + \frac{13}{16} = 22\frac{13}{16}$$ в) $$\frac{6}{25} \cdot \frac{5}{18} = \frac{6 \cdot 5}{25 \cdot 18} = \frac{30}{450} = \frac{3}{45} = \frac{1}{15}$$ г) $$\frac{5}{9} : \frac{10}{27} = \frac{5}{9} \cdot \frac{27}{10} = \frac{5 \cdot 27}{9 \cdot 10} = \frac{135}{90} = \frac{27}{18} = \frac{3}{2} = 1\frac{1}{2} = 1,5$$