a) 0,4n - 0,7m - 0,9n + 0,7m; г) 7/9x - 3/4 - 11/18x - 1/4; д) 0,3m - 2/7 - 3m + 6/7;

a)

• \[ 0.4n - 0.7m - 0.9n + 0.7m = (0.4 - 0.9)n + (-0.7 + 0.7)m = -0.5n + 0m = -0.5n \]

г)

• \[ \frac{7}{9}x - \frac{3}{4} - \frac{11}{18}x - \frac{1}{4} = \left( \frac{7}{9} - \frac{11}{18} \right)x + \left( -\frac{3}{4} - \frac{1}{4} \right) = \left( \frac{14}{18} - \frac{11}{18} \right)x - \frac{4}{4} = \frac{3}{18}x - 1 = \frac{1}{6}x - 1 \]

д)

• \[ 0.3m - \frac{2}{7} - 3m + \frac{6}{7} = (0.3 - 3)m + \left( -\frac{2}{7} + \frac{6}{7} \right) = -2.7m + \frac{4}{7} \]

Ответ: a) -0.5n; г) 1/6x - 1; д) -2.7m + 4/7