A) 9 . (3x - 1) - 5 = 20x
27x - 9 - 5 = 20x
27x - 20x = 9 + 5
7x = 14
x = 14 ÷ 7
x = 2

b) 3 . (x + 1) + 31 = 2 . (3x + 5)
3x + 3 + 31 = 6x + 10
3x - 6x = 10 - 3 - 31
- 3x = - 24
x = - 24 ÷ (- 3)
x = 8

c) 2x - 2 =  x  + 4      
     5           4
mmc (4, 5) = 20
8x - 40 = 5x + 80
8x - 5x = 80 + 40
3x = 120
x = 120 ÷ 3
x = 40

d) x - x   = 8
         9      3
mmc (3, 9) = 9
9x - x = 24
8x = 24
x = 24 ÷ 8
x = 3

e) 5x - 3x - 9 = 9
    4           6    2
mmc (2, 4, 6) = 12
15x - 36x - 18 = 54
- 21x = 54 + 18
- 21x = 72
x = 72 ÷ (- 21)
x = - 24/7