a) \(20x + y - 20y - x = (20x - x) + (y - 20y) = 19x - 19y\)
б) \(-4b + 5a + 4b + 5a = (5a + 5a) + (-4b + 4b) = 10a + 0b = 10a\)
в) \(-9c + 4,8n + 4c + 4n = (-9c + 4c) + (4,8n + 4n) = -5c + 8,8n\)
г) \(5,3m + 4,7m - 7,1x + 25x = (5,3m + 4,7m) + (-7,1x + 25x) = 10m + 17,9x\)
д) \(\frac{3}{4}z - \frac{4}{9}y - \frac{7}{22}z + \frac{2}{3}y = (\frac{3}{4}z - \frac{7}{22}z) + (-\frac{4}{9}y + \frac{2}{3}y) = (\frac{33}{44}z - \frac{14}{44}z) + (-\frac{4}{9}y + \frac{6}{9}y) = \frac{19}{44}z + \frac{2}{9}y\)