a/ 4x+20=10x+3
4x-10x= 3-20
-6x=-17
x= -17/-6
b/ 3x-6=6x+24
3x-6x= 24 +6
-3x= 30
x=30/-3= -10
c/ -35x au carré +21x =5x-15+2
-35x au carre +21x -5x =-13
-35x au carre +16x = -13
d/ 7n+14 -3 = 25 -3n -4
7n +3n = -14 +3 -4
10n= -15
n =- 15/10 = - 3/2
e/ 4y+12y-6 = 3y +3
4y+12y-3y = 6+3
13y =9
y=9/13
