a) (3x - 6)/3 - 5 = 3(x - 2)/3 - 5 = x - 2 - 5 = x - 7
b) (3a - 9b)/3 - (2a - 4b)/2 = 3(a - 3b)/3 - 2(a - 2b)/2 = a - 3b - a + 2b = -b
c) (2x + 6)/2 - (6x - 9)/3 = 2(x + 3)/2 - 3(2x - 3)/3 = x + 3 - 2x + 3 = - x + 6
d)4 * (x - 7)/2 + 9 * (x - 1)/3 = 4(x - 7)/2 + 9(x - 1)/3 = 2x - 14 + 3x - 3 = 5x - 17
