Решение:
а) $\frac{1}{2} - (-\frac{1}{3}) = \frac{1}{2} + \frac{1}{3} = \frac{3}{6} + \frac{2}{6} = \frac{3 + 2}{6} = \frac{5}{6};$
б) $\frac{4}{9} - (-\frac{7}{9}) = \frac{4}{9} + \frac{7}{9} = \frac{4 + 7}{9} = \frac{11}{9} = 1\frac{2}{9};$
в) $-\frac{9}{16} - (-\frac{3}{8}) = -\frac{9}{16} + \frac{3}{8} = -\frac{9}{16} + \frac{6}{16} = \frac{-9 + 6}{16} = -\frac{3}{16};$
г) $-\frac{1}{2} - (-\frac{3}{8}) = -\frac{1}{2} + \frac{3}{8} = -\frac{4}{8} + \frac{3}{8} = \frac{-4 + 3}{8} = -\frac{1}{8};$
д) $-\frac{9}{10} - (-\frac{15}{16}) = -\frac{9}{10} + \frac{15}{16} = -\frac{72}{80} + \frac{75}{80} = \frac{-72 + 75}{80} = \frac{3}{80};$
е) $\frac{25}{26} - (-\frac{11}{13}) = \frac{25}{26} + \frac{11}{13} = \frac{25}{26} + \frac{22}{26} = \frac{47}{26} = 1\frac{21}{26}.$
Ответ:
а) $\frac{5}{6};$
б) $1\frac{2}{9};$
в) $-\frac{3}{16};$
г) $-\frac{1}{8};$
д) $\frac{3}{80};$
е) $1\frac{21}{26}$.