Выполните действия.
а) $(\frac{31}{47} - \frac{6}{47}) - (\frac{11}{47} - \frac{6}{47})$
б) $(\frac{29}{53} - \frac{9}{53}) - (\frac{21}{53} - \frac{9}{53})$
в) $\frac{17}{27} - (\frac{2}{27} + (\frac{9}{27} - \frac{4}{27}))$
г) $\frac{18}{29} - (\frac{3}{29} + (\frac{16}{29} - \frac{11}{29}))$

$(\frac{31}{47} - \frac{6}{47}) - (\frac{11}{47} - \frac{6}{47}) = \frac{25}{47} - \frac{5}{47} = \frac{20}{47}$
$(\frac{29}{53} - \frac{9}{53}) - (\frac{21}{53} - \frac{9}{53}) = \frac{20}{53} - \frac{12}{53} = \frac{8}{53}$
$\frac{17}{27} - (\frac{2}{27} + (\frac{9}{27} - \frac{4}{27})) = \frac{17}{27} - (\frac{2}{27} + \frac{5}{27}) = \frac{17}{27} - \frac{7}{27} = \frac{10}{27}$
$\frac{18}{29} - (\frac{3}{29} + (\frac{16}{29} - \frac{11}{29})) = \frac{18}{29} - (\frac{3}{29} + \frac{5}{29}) = \frac{18}{29} - \frac{8}{29} = \frac{10}{29}$