bjr
on a donc
x + (-4) + 5 + 2y = 13
soit
x + 2y + 1 = 13
x + 2y = 12
et
2x + 5 + (-3) + 4 = 13
2x + 6 = 13
2x = 7
x = 7/2
et donc 7/2 + 2y = 12
2y = 12 - 7/2
2y = 17/2
x = 17/4