Respuesta :

klove5

Answer:

9x+15y+2z

Step-by-step explanation:

- just combine like terms

6x+7y-4z-2x+3y-z+5x+5y+7z

9x+7y-4z+3y-z+5y+7z

9x+15y-4z-z+7z

9x+15y+2z