Explications étape par étape:
b. x + 4 = x + 8
- x - 8 -x -8
0 = x -
c. 5x + 4 = 10x +8
-10x - 4 -10x -4
- 5x = 4
-5x ÷ -5 = 4 ÷ 5 = 0,8
x = 0,8
d. 15x + 4 = 5x + 4
- 5x -4 -5x - 4
10x = 0
10x ÷ 10 = 0 ÷ 10 = 0
x = 0
