Réponse:
4x - 2 = 18
4x = 18 + 2
4x = 20
x = 20 : 4
x = 5
-2x + 5 = -7
-2x = 7 - 5
-2x = 2
x = 2 : -2
x = -1
7x - 4 = 8x - 11
7x - 8x = -11 + 4
-1x = -7
x = -7 : -1
x = 7
3(2x -4) = 4(2x -5)
6x - 12 = 8x -20
6x - 8x = -20 + 12
-2x = -8
x = -8 : -2
x = 4