в) 4/9 + (1/9 - 2/3); г) -(3,69 - 6/13) - (1,31 - 8/11); д) x - (y + x);

Решение:

в) \[ \frac{4}{9} + \left( \frac{1}{9} - \frac{2}{3} \right) = \frac{4}{9} + \left( \frac{1}{9} - \frac{6}{9} \right) = \frac{4}{9} + \left( -\frac{5}{9} \right) = \frac{4}{9} - \frac{5}{9} = -\frac{1}{9} \] г) \[ -\left( 3,69 - \frac{6}{13} \right) - \left( 1,31 - \frac{8}{11} \right) = -3,69 + \frac{6}{13} - 1,31 + \frac{8}{11} = (-3,69 - 1,31) + \left( \frac{6}{13} + \frac{8}{11} \right) = -5 + \left( \frac{66 + 104}{143} \right) = -5 + \frac{170}{143} = -5 + 1 \frac{27}{143} = -3 \frac{116}{143} \] д) \[ x - (y + x) = x - y - x = -y \]

Ответ: в) -1/9; г) -3 116/143; д) -y