26. Выполните действия: a) 4\(\frac{3}{8}\) - (3\(\frac{5}{7}\) - 1\(\frac{5}{7}\)) + 1\(\frac{5}{8}\); б) 12\(\frac{7}{12}\) - 4\(\frac{5}{12}\) - (20\(\frac{3}{4}\) - 19\(\frac{3}{4}\)).

Решение:

• a) \( 4\frac{3}{8} - (3\frac{5}{7} - 1\frac{5}{7}) + 1\frac{5}{8} = 4\frac{3}{8} - 2\frac{5}{7} + 1\frac{5}{8} \). Приведем дроби к общему знаменателю \( 56 \): \( 4\frac{21}{56} - 2\frac{40}{56} + 1\frac{35}{56} = \frac{4 \cdot 56 + 21}{56} - \frac{2 \cdot 56 + 40}{56} + \frac{1 \cdot 56 + 35}{56} = \frac{253}{56} - \frac{152}{56} + \frac{91}{56} = \frac{253 - 152 + 91}{56} = \frac{101 + 91}{56} = \frac{192}{56} = \frac{24}{7} = 3\frac{3}{7} \).
• б) \( 12\frac{7}{12} - 4\frac{5}{12} - (20\frac{3}{4} - 19\frac{3}{4}) = 12\frac{7}{12} - 4\frac{5}{12} - 1 = (12 - 4)\frac{7-5}{12} - 1 = 8\frac{2}{12} - 1 = 8\frac{1}{6} - 1 = 7\frac{1}{6} \).

Ответ: a) \(3\frac{3}{7}\), б) \(7\frac{1}{6}\)