Réponse:
4x = 30
4x/4 = 30/4
x = 30/4
x = 15/2
x +8 = 25
x = 25 -8
x = 17
5x = -15
5x/5 = -15/5
x = -3
x +6 = -10
x = -10 -6
x = -16
x -7 = 13
x = 13+7
x = 20
x -3 = -5
x = -5 +3
x = -2
2x +4 = 20
2x = 20 -4
2x = 16
2x/2 = 16/2
x = 8
4x -2 = 10
4x = 10 +2
4x = 12
4x/4 = 12/4
x = 3
8x +3 = 12
8x = 12 -3
8x = 9
8x/8 = 9/8
x = 9/8
-2x +7 = 0
-2x = -7
-2x/-2 = -7/-2
x = 7/2
3x -5 = -20
3x = -20 +5
3x = -15
3x/3 = -15/3
x = -5
7x -6 = 1
7x = 1 +6
7x = 7
7x/7 = 7/7
x = 1