Find equation of the plane

Question

Guys, how do I find an equation of the plane just by looking at a certain graph? I have an assignment from this book that asks me to do this... If anyone can help me, please take a look at:

https://m.imgur.com/gallery/07jwn

I don't know if i can put images in here so i posted on imgur...
If anyone can help me with this one i would really appreciate!

Answer 1

Note the plane that is unrestricted.

7. z is unrestricted, y = x

8. z is unrestricted, y = -x + 1

9. x is unrestricted, y = -z + 1

10. x is unrestricted, y = z