bonjour
12 + x = 5 - 13 x
x + 13 x = 5 - 12
14 x = - 7
x = - 7/14 = - 1 /7
7 x - 8 = 3 x+ 2
7 x - 3 x = 2 + 8
4 x = 10
x = 10/4 = 5/2
x /5 + 11 = - 9
x /5 + 55/5 = - 45/5
x = - 45 - 55
x = - 100
5 - x /2 = 1 /2
10/2 - x /2 = 1/2
- x = 1 - 10
- x = - 9
x = 9
3 x /2 + x /3 - 1 = 1 /3
9 x /6 + 2 x /6 - 6 /6 = 2 /6
11 x = 2 + 6
11 x = 8
x = 8/ 11
3 x /2 + 1 = x /4 - 1
6 x / 4 + 4 /4 = x /4 - 4/4
6 x - x = - 4 - 4
5 x = - 8
x = - 8/5