Sagot :
7y + 9(y-2)
Distributivité
x(a-b) = xa-xb
6(a+1)+8(3+a)
Distributivité
x(a+b)=xa+xb
13+5(3-x)
Distributivité
7y +9(y-2) = 7y +9y -18 = 16y -18
6(a+1) +8 (3+a) = (6a+6)+(24+8a)
= 6a +6 +24+8a = 14a +30
13 +5(3-x) = 13+15-5x = -5x +28