Salut,
3x = 9
x= 9/3 = 3
5y = 3
y = 3/5 = 0,6
4z = -7
z = -7/4 = -1, 75
-2z = -8
z = -8/(-2) = 4
7x = 4
x = 4/7
- y = - 7,2
y = 7, 2
- y = 15,7
y = -15, 7
4,4z = 0
z = 0/4, 4 = 0
2,7x = -1, 2
x= -1, 2/2, 7
J'espère t'avoir aidé !
Dreamus