Решение:
а) $\frac{-2}{7} - \frac{-5}{7} = \frac{-2 - (-5)}{7} = \frac{-2 + 5}{7} = \frac{3}{7};$
б) $\frac{-4}{9} - \frac{-8}{9} = \frac{-4 - (-8)}{9} = \frac{-4 + 8}{9} = \frac{4}{9};$
в) $-\frac{1}{10} - \frac{-7}{10} = \frac{-1 - (-7)}{10} = \frac{-1 + 7}{10} = \frac{6}{10} = \frac{3}{5};$
г) $-\frac{12}{19} - \frac{7}{19} = \frac{-12 - 7}{19} = \frac{-12 - 7}{19} = \frac{-19}{19} = -1;$
д) $\frac{-4}{5} - \frac{-3}{5} = \frac{-4 - (-3)}{5} = \frac{-4 + 3}{5} = \frac{-1}{5} = -\frac{1}{5};$
е) $-\frac{1}{24} - \frac{11}{24} = \frac{-1 - 11}{24} = \frac{-12}{24} = \frac{-1}{2} = -\frac{1}{2}.$
Ответ:
а) $\frac{3}{7};$
б) $\frac{4}{9};$
в) $\frac{3}{5};$
г) −1;
д) $-\frac{1}{5};$
е) $-\frac{1}{2}.$