5x - 7 = 8
5x - 7 + 7 = 8 + 7
5x = 15
5/5x = 15/5
x = 3
-2 = 18 + 10y
10y + 18 = - 2
10y + 18 - 18 = - 2 - 18
10y = -20
10/10y = -20/10
y = -2
idem pour le c
d
3*x + 3*(-1) = 3
3x - 3 = 3
vous finissez
e
12 - 12 - 6x = 3/2 - 12
-6x = 3/2 - 24/2
-6x = -21/2
6x = 21/2
6/6x = 21/2 /6
x = 21/2 * 1/6
x= 21/12
x = 3x7/3x4
x = 7/4
x = 1,75
f
5/3x - 2/3x = -1/5
x = -1/5
x = -0,2
