je n'y arrive pas aider moi svp

A= 3x+4x+5+10
= 7x+15

B= 6x+6y+z

C=3x+4x+y
=7x+y

D= 9x+8x+4x-3
=21x-3

E= 4x+15

F= 2x+2y+3x+4y
=5x+6y

G= 3x+3y+7x+7y
=10x+10y

H= 7x+18

I= 7x+2x-3
=9x-3