bjr
4y+2=30
4y + 2 - 2 = 30 - 2
4y = 28
4y/4y = 28/4
y = 7
on a bien 4*7 + 2 = 30
13-2y=20
13 - 13 - 2y = 20 - 13
-2y = 7
-2y/(-2) = 7/(-2)
y = -3,5
on a bien 13 - 2*(-3,5) = 20
3t-9=11
3t - 9 + 9 = 11 + 9
3t = 20
3t/3 = 20/3
t = 20/3
on a bien 3 *(20/3) - 9 = 20 - 9 = 11
