a) $$(\frac{3}{2} - \frac{6}{5}) : \frac{9}{8} = (\frac{15}{10} - \frac{12}{10}) : \frac{9}{8} = \frac{3}{10} : \frac{9}{8} = \frac{3}{10} \cdot \frac{8}{9} = \frac{1}{5} \cdot \frac{4}{3} = \frac{4}{15}$$
б) $$10 : \frac{5}{2} - \frac{10}{3} = 10 \cdot \frac{2}{5} - \frac{10}{3} = 4 - \frac{10}{3} = \frac{12}{3} - \frac{10}{3} = \frac{2}{3}$$
в) $$2 \frac{3}{2} : (\frac{5}{2} + \frac{15}{4}) = \frac{7}{2} : (\frac{10}{4} + \frac{15}{4}) = \frac{7}{2} : \frac{25}{4} = \frac{7}{2} \cdot \frac{4}{25} = \frac{7}{1} \cdot \frac{2}{25} = \frac{14}{25}$$
г) $$(1 \frac{1}{2} + \frac{8}{3}) : 3 = (\frac{3}{2} + \frac{8}{3}) : 3 = (\frac{9}{6} + \frac{16}{6}) : 3 = \frac{25}{6} : 3 = \frac{25}{6} \cdot \frac{1}{3} = \frac{25}{18}$$
Ответ: а) $$\frac{4}{15}$$; б) $$\frac{2}{3}$$; в) $$\frac{14}{25}$$; г) $$\frac{25}{18}$$