Respuesta :

3x+3y+3z=18 

Start by subtracting both sides by 3z

3x + 3y = 18 - 3z 

Now , you can subtract 3y from both sides....

3x = - 3z - 3y + 18 

Finally .... To get x by itself divide both sides by 3.......

x = - z - y + 6 is the answer