2.193. Выполните действия: а) 1/5 + 1/7; б) 1/3 + 2/7; в) 3/5 + 5/6; г) 8/9 − 2/5; д) 5/12 + 1/6; е) 3/5 − 4/15; ж) 19/21 − 11/15; з) 5/42 + 10/63; и) 11/21 + 2/26; к) 5/24 − 7/60.

1. \(\frac{1}{5} + \frac{1}{7} = \frac{7}{35} + \frac{5}{35} = \frac{12}{35}\).
2. \(\frac{1}{3} + \frac{2}{7} = \frac{7}{21} + \frac{6}{21} = \frac{13}{21}\).
3. \(\frac{3}{5} + \frac{5}{6} = \frac{18}{30} + \frac{25}{30} = \frac{43}{30} = 1\frac{13}{30}\).
4. \(\frac{8}{9} - \frac{2}{5} = \frac{40}{45} - \frac{18}{45} = \frac{22}{45}\).
5. \(\frac{5}{12} + \frac{1}{6} = \frac{5}{12} + \frac{2}{12} = \frac{7}{12}\).
6. \(\frac{3}{5} - \frac{4}{15} = \frac{9}{15} - \frac{4}{15} = \frac{1}{3}\).
7. \(\frac{19}{21} - \frac{11}{15} = \frac{95}{105} - \frac{77}{105} = \frac{18}{105} = \frac{6}{35}\).
8. \(\frac{5}{42} + \frac{10}{63} = \frac{15}{126} + \frac{20}{126} = \frac{35}{126} = \frac{5}{18}\).
9. \(\frac{11}{21} + \frac{2}{26} = \frac{11}{21} + \frac{1}{13} = \frac{143}{273} + \frac{21}{273} = \frac{164}{273}\).
10. \(\frac{5}{24} - \frac{7}{60} = \frac{25}{120} - \frac{14}{120} = \frac{11}{120}\).

Ответ: а) 12/35; б) 13/21; в) 1 13/30; г) 22/45; д) 7/12; е) 1/3; ж) 6/35; з) 5/18; и) 164/273; к) 11/120.