1) [tex]\frac{7}{36} + \frac{1}{5} + \frac{5}{36} = \frac{1}{5} + \frac{12}{36} = \frac{1}{5} + \frac{1}{3} = \frac{3}{15} + \frac{5}{15} = \frac{8}{15}[/tex]

2) [tex](\frac{1}{6} + \frac{7}{15}) - \frac{2}{15} = \frac{1}{6} + \frac{7}{15} - \frac{2}{15} = \frac{1}{6} + \frac{1}{3} = \frac{3}{18} + \frac{6}{18} = \frac{9}{18} = \frac{1}{2}[/tex]

3) [tex]\frac{19}{42} - (\frac{5}{42} + \frac{1}{5}) = \frac{19}{42} - \frac{5}{42} - \frac{1}{5} = \frac{14}{42} - \frac{1}{5} = \frac{1}{3} - \frac{1}{5} = \frac{5}{15} - \frac{3}{15} = \frac{2}{15}[/tex]

Надеюсь помог!!!