/sci/ - Science & Math

So i'm working through a LA textbook, and i'm at the end of chapter 3 (span, basis, dimensions).

I thought i was doing ok, i thought i was getting the answers right, and then i came to this question.

I completely do not understand how the answer is obtained.

From elimination I come out to
1 3 4
0 -5 -5
0 0 0

and i don't know what to do now to get that answer.

Also when it asks for a basis, does it mean column or row?