Réponse:
a) x + 2 = 3 | 4x + 8 = 12
×= 3-2 = 1 | 4x = 12-8 = 4 ; x=4÷4=1
b) x - 3 = -5 | -6x + 18 = 30
x=-5+3=-2 | -6x=30-18=12; x = 12÷(-6)=-2
c) x + 4 = 7 | 5x + 20 = 7
x=7-4=3 | 5x= 7-20 = -13 ; x=-13÷5= -2,5
d) x + 5 = 11 | x/2 + 5/2 = 11/2
x=11-5= 6 | 1/2 x + 2,5=6 ; 1/2x=6-2,5 = 3,5; x = 3,5÷0,5=7
