a) $$5\frac{7}{12}-2\frac{4}{9}+1\frac{5}{18}$$; б) $$10-3\frac{4}{5}-5\frac{2}{3}$$.

a) Приведем дроби к общему знаменателю 36: $$5\frac{7}{12}-2\frac{4}{9}+1\frac{5}{18} = 5\frac{21}{36}-2\frac{16}{36}+1\frac{10}{36} = (5-2+1) + (\frac{21}{36}-\frac{16}{36}+\frac{10}{36}) = 4 + \frac{21-16+10}{36} = 4+\frac{15}{36} = 4+\frac{5}{12} = 4\frac{5}{12}$$ б) $$10-3\frac{4}{5}-5\frac{2}{3} = 10-\frac{19}{5}-\frac{17}{3} = 10-\frac{19\cdot 3}{5\cdot 3}-\frac{17\cdot 5}{3\cdot 5} = 10-\frac{57}{15}-\frac{85}{15} = 10-\frac{57+85}{15} = 10-\frac{142}{15} = 10-9\frac{7}{15} = \frac{150}{15}-\frac{142}{15} = \frac{8}{15}$$ Ответ: а) $$4\frac{5}{12}$$ б) $$\frac{8}{15}$$