$(x + \frac{4}{7}) - \frac{9}{14} = \frac{1}{4}$
$x + \frac{4}{7} = \frac{1}{4} + \frac{9}{14}$
$x + \frac{4}{7} = \frac{1}{4}^{/7} + \frac{9}{14}^{/2}$
$x + \frac{4}{7} = \frac{7}{28} + \frac{18}{28}$
$x + \frac{4}{7} = \frac{25}{28}$
$x = \frac{25}{28} - \frac{4}{7}^{/4}$
$x = \frac{25}{28} - \frac{16}{28}$
$x = \frac{9}{28}$
Ответ: $x = \frac{9}{28}$

$(x - \frac{17}{36}) + \frac{9}{40} = \frac{13}{30}$
$x - \frac{17}{36} = \frac{13}{30}^{/4} - \frac{9}{40}^{/3}$
$x - \frac{17}{36} = \frac{52}{120} - \frac{27}{120}$
$x - \frac{17}{36} = \frac{25}{120}$
$x - \frac{17}{36} = \frac{5}{24}$
$x = \frac{5}{24}^{/3} + \frac{17}{36}^{/2}$
$x = \frac{15}{72} + \frac{34}{72}$
$x = \frac{49}{72}$
Ответ: $x = \frac{49}{72}$

$2\frac{3}{4} - (x - 3\frac{1}{8}) = 1\frac{1}{6}$
$x - 3\frac{1}{8} = 2\frac{3}{4}^{/3} - 1\frac{1}{6}^{/2}$
$x - 3\frac{1}{8} = 2\frac{9}{12} - 1\frac{2}{12}$
$x - 3\frac{1}{8} = 1\frac{7}{12}$
$x = 1\frac{7}{12}^{/2} + 3\frac{1}{8}^{/3}$
$x = 1\frac{14}{24} + 3\frac{3}{24}$
$x = 4\frac{17}{24}$
Ответ: $x = 4\frac{17}{24}$

$7\frac{5}{9} - (3\frac{4}{27} - x) = 2\frac{5}{6}$
$3\frac{4}{27} - x = 7\frac{5}{9}^{/2} - 2\frac{5}{6}^{/3}$
$3\frac{4}{27} - x = 7\frac{10}{18} - 2\frac{15}{18}$
$3\frac{4}{27} - x = 6\frac{28}{18} - 2\frac{15}{18}$
$3\frac{4}{27} - x = 4\frac{13}{18}$
$x = 3\frac{4}{27} - 4\frac{13}{18}$ < 0