Help with Two Situations

I've been given two situations and asked to say what the outcome will be, however I am completly lost.

1)

Code:
x + y + 4z = 6
-10y -14z = 2
0z = 122
2)

Code:
x + y + 4z = 6
-10y -14z = 2
0z = 0
I'm not sure about 1, but for 2 would it mean that z has inifinte values as it is undefined. How can I solve these?

Thanks