5.412 Выполните действия:

Решение:

1. \( \frac{7}{9} - \frac{5}{12} = \frac{28}{36} - \frac{15}{36} = \frac{13}{36} \)
2. \( \frac{5}{6} + \frac{7}{8} = \frac{20}{24} + \frac{21}{24} = \frac{41}{24} = 1\frac{17}{24} \)
3. \( \frac{11}{21} + \frac{3}{7} = \frac{11}{21} + \frac{9}{21} = \frac{20}{21} \)
4. \( 13\frac{21}{22} - 11\frac{3}{55} = 13\frac{105}{110} - 11\frac{6}{110} = 2\frac{99}{110} = 2\frac{9}{10} \)
5. \( 8\frac{5}{40} + \frac{7}{60} = 8\frac{1}{8} + \frac{7}{60} = 8\frac{15}{120} + \frac{14}{120} = 8\frac{29}{120} \)
6. \( \frac{17}{21} - \frac{8}{15} = \frac{85}{105} - \frac{56}{105} = \frac{29}{105} \)

Ответ: a) \( \frac{13}{36} \), б) \( 1\frac{17}{24} \), д) \( \frac{20}{21} \), е) \( 2\frac{9}{10} \), ж) \( 8\frac{29}{120} \), з) \( \frac{29}{105} \).