1015. Выполните действия: a) 2/11 + 5/11; b) 6/15 - 4/15; д) 3/9 + 2/9; ж) 12/19 - 1/19 - 5/19; б) 1/8 + 4/8; г) 11/25 - 3/25; e) 5/18 + 12/18 - 9/18; з) 25/23 - 10/23 + 3/23.

Решение:

• a) \(\frac{2}{11} + \frac{5}{11} = \frac{2 + 5}{11} = \frac{7}{11}\)
• b) \(\frac{6}{15} - \frac{4}{15} = \frac{6 - 4}{15} = \frac{2}{15}\)
• д) \(\frac{3}{9} + \frac{2}{9} = \frac{3 + 2}{9} = \frac{5}{9}\)
• ж) \(\frac{12}{19} - \frac{1}{19} - \frac{5}{19} = \frac{12 - 1 - 5}{19} = \frac{6}{19}\)
• б) \(\frac{1}{8} + \frac{4}{8} = \frac{1 + 4}{8} = \frac{5}{8}\)
• г) \(\frac{11}{25} - \frac{3}{25} = \frac{11 - 3}{25} = \frac{8}{25}\)
• e) \(\frac{5}{18} + \frac{12}{18} - \frac{9}{18} = \frac{5 + 12 - 9}{18} = \frac{8}{18} = \frac{4}{9}\)
• з) \(\frac{25}{23} - \frac{10}{23} + \frac{3}{23} = \frac{25 - 10 + 3}{23} = \frac{18}{23}\)