99. Выполните действия: а) \(\left(3\frac{7}{30}-1\frac{5}{12}\right):18\frac{1}{6}\); б) \((1,5+2\frac{2}{3}):1\frac{2}{3}\); в) \(\left(\frac{11}{18}-1\frac{7}{12}\right)\cdot\left(2\frac{1}{6}+\frac{7}{30}\right)\); г) \((3,4-5)\cdot\left(\frac{31}{48}+\frac{7}{24}\right)\).

а) \(3\frac{7}{30}=\frac{97}{30}\), \(1\frac{5}{12}=\frac{17}{12}\), поэтому \(\frac{97}{30}-\frac{17}{12}=\frac{109}{60}\). Тогда \(\frac{109}{60}:\frac{109}{6}=\frac{1}{10}\).

б) \(1,5+2\frac{2}{3}=\frac{3}{2}+\frac{8}{3}=\frac{25}{6}\). Тогда \(\frac{25}{6}:\frac{5}{3}=\frac{5}{2}\).

в) \(\frac{11}{18}-1\frac{7}{12}=\frac{22}{36}-\frac{57}{36}=-\frac{35}{36}\), а \(2\frac{1}{6}+\frac{7}{30}=\frac{13}{6}+\frac{7}{30}=\frac{12}{5}\). Поэтому \(-\frac{35}{36}\cdot\frac{12}{5}=-\frac{7}{3}\).

г) \(3,4-5=-1,6=-\frac{8}{5}\), \(\frac{31}{48}+\frac{7}{24}=\frac{31}{48}+\frac{14}{48}=\frac{15}{16}\). Поэтому \(-\frac{8}{5}\cdot\frac{15}{16}=-\frac{3}{4}\).

Ответ: а) \(\frac{1}{10}\); б) \(\frac{5}{2}\); в) \(-\frac{7}{3}\); г) \(-\frac{3}{4}\).