bonjour
2 x + 3 y = 7
- 8 x + y = - 2
8 x + 12 y = 28
13 y = 26
y = 2
2 x + 3 *2 = 7
2 x + 6 = 7
2 x = 7 - 6
2 x = 1
x = 0.5
- 4 + 2 = - 2