Ответ:
(21) \(27-11\frac{7}{9}=15\frac{2}{9}\).
(22) \(2\frac{7}{12}-1\frac{13}{24}=2\frac{14}{24}-1\frac{13}{24}=1\frac{1}{24}\).
(23) \(8-3\frac{1}{12}=7\frac{12}{12}-3\frac{1}{12}=4\frac{11}{12}\).
Ответ: (21) \(15\frac{2}{9}\); (22) \(1\frac{1}{24}\); (23) \(4\frac{11}{12}\).
