bonjour
12 + 3 x = 7 x + 10
3 x - 7 x = 10 - 12
- 4 x = - 2
x = 2
- 3 x - 4 = 5 + x
- 3 x - x = 5 + 4
- 4 x = 9
x = - 9/4
4 x - 9 = - 6 + 12 x
4 x - 12 x = - 6 + 9
- 8 x = 3
x = - 3/8
2 + 5 x = - 2 x - 3
5 x + 2 x = - 3 - 2
7 x = - 5
x = - 5/7
4 x - 1 = 14 + x
4 x - x = 14 + 1
3 x = 15
x = 15/3 = 5
continue