Bonjour
a. 4 (2 - x) + 5 = 3 (2x + 3) - 12
8 - 4x + 5 = 6x + 9 - 12
- 4x - 6x = 9 - 12 - 8 - 5
- 10x = - 16
x = 16/10
x = 1,6
b. (3x + 1) / 4 = (5x - 2) / 5
15x + 5 = 20x - 8
15x - 20x = - 8 - 5
- 5x = - 13
x = 13/5
c. x/3 + 5/6 = 1/2 - x
x/3 + x = 1/2 - 5/6
2x + 6x = 3 - 5
8x = - 2
x = - 2/8
x = - 1/4.
d. x - (x + 1) = (x + 3) - (x - 3)
x - x - 1 = x + 3 - x + 3
x - x - x + x = 3 + 3 + 1
0x = 5
Impossible.
