5.412 Выполните действия: a) 7/9 - 5/12; б) 11/12 - 11/20; в) 5/6 + 7/8; г) 17/21 - 8/15; д) 13 21/22 - 11 3/55; e) 8 5/40 + 7 10/60.

5.412 Выполните действия:

a) \( \frac{7}{9} - \frac{5}{12} = \frac{28}{36} - \frac{15}{36} = \frac{13}{36} \)

б) \( \frac{11}{12} - \frac{11}{20} = \frac{55}{60} - \frac{33}{60} = \frac{22}{60} = \frac{11}{30} \)

в) \( \frac{5}{6} + \frac{7}{8} = \frac{20}{24} + \frac{21}{24} = \frac{41}{24} = 1 \frac{17}{24} \)

г) \( \frac{17}{21} - \frac{8}{15} = \frac{85}{105} - \frac{56}{105} = \frac{29}{105} \)

д) \( 13 \frac{21}{22} - 11 \frac{3}{55} = 13 \frac{105}{110} - 11 \frac{6}{110} = 2 \frac{99}{110} = 2 \frac{9}{10} \)

е) \( 8 \frac{5}{40} + 7 \frac{10}{60} = 8 \frac{1}{8} + 7 \frac{1}{6} = 8 \frac{3}{24} + 7 \frac{4}{24} = 15 \frac{7}{24} \)