Ответ:

а) \(12\frac{1}{3}-11\frac{1}{4}=\frac{1}{12}\), а \(14-9\frac{8}{15}=4\frac{7}{15}\).

\(\frac{1}{12}+4\frac{7}{15}=4\frac{29}{60}\).

б) \(15-12\frac{5}{8}=2\frac{3}{8}\), а \(13\frac{1}{2}-11\frac{2}{9}=2\frac{5}{18}\).

\(2\frac{3}{8}-2\frac{5}{18}=\frac{7}{72}\).

в) \(14\frac{2}{3}-5\frac{5}{9}=9\frac{1}{9}\); \(3\frac{7}{8}+4\frac{5}{6}=8\frac{17}{24}\); \(10\frac{3}{4}-4\frac{4}{9}=6\frac{11}{36}\).

\(9\frac{1}{9}-8\frac{17}{24}+6\frac{11}{36}=\frac{5}{12}+6\frac{11}{36}=6\frac{13}{18}\).

г) \(14\frac{5}{7}-14=\frac{5}{7}\), \(30-29\frac{5}{7}=\frac{2}{7}\), \(3\frac{1}{7}-\frac{23}{28}=2\frac{9}{28}\).

\(\frac{5}{7}+\frac{2}{7}+2\frac{9}{28}=3\frac{5}{28}\).

Ответ: а) \(4\frac{29}{60}\); б) \(\frac{7}{72}\); в) \(6\frac{13}{18}\); г) \(3\frac{5}{28}\).