bonjour
2 a - 4 b = 6
3 a - 7 b = 8
- 6 a + 12 b = - 18
6 a - 14 b = 16
- 2 b = - 2
b = 1
2 a - 4 = 6
2 a = 6 + 4
2 a = 10
a = 5
