4) (x+1)+(x-2)+(x+2)=x+12 8(x-2)=2x-4 12(x-5)=7(x-2) 5(x-4)=7(x-3)-(x+4)

(x+1)+(x-2)+(x+2)=x+12
x+1+x-2+x+2=x+12
x+x+x-x=12-1+2-2
2x=11
x=11/2

8(x-2)=2x-4
8x-16=2x-4
8x-2x=-4+16
6x=12
x=12/6 ou 2

12(x-5)=7(x-2)
12x-60=7x-14
12x-7x=-14+60
5x=46
x=46/5

5(x-4)=7(x-3)-(x+4)
5x-20=7x-21-x-4
5x-7x+x=-21-4+20
-x=-5
x=5