Bonjour,
1) 5x + 7 = -5 + 11x
5x + 7 - 7 = -5 + 11x -7
5x = -11 + 11x
5x - 11x = -11 + 11x - 11x
-6x = -11
x = -11/-6 ≈ 1.8
2) 3x - 4 = 2x + 9
3x - 4 + 4 = 2x + 9 + 4
3x = 2x + 13
3x - 2x = 2x - 2x + 13
x = 13
3). 2(5-3x) = 6(2x + 1)
10 - 6x = 3x + 6
10 - 10 - 6x = 3x + 6 - 10
-6x = 3x -4
-6x - 3x = 3x - 3x -4
-9x = -4
x = -4/-9 ≈ 0.4
4). 2x + 1 = 4(x-2) + x
2x + 1 = 4x - 8
2x + 1 - 1 = 4x - 8 + 1
2x = 4x -7
2x - 4x = 4x - 4x - 7
-2x = -7
X = -7/-2 = 3.5
