I seriously don't get anything I am learning right now. I paid attention to the notes, but honestly, I just don't even get where to start. We are learning

SOLVING LINEAR SYSTEMS WITH THREE VARIABLES. DOES anyone KNOW how do this? It's for extra credit, which I need so desperately I have been trying to understand this for an hour with videos one youtube and it's not working at all :/ I am going to try again. If someone could teach me with one problem clearly I can probably get it. Here's a problem

8x + 2y - Z = -25
3x - 3y + 5z = 10
-5x + 6y - 2z = 17


If no one gets it I understand, Cause I certainly don't but this is worth a try posting. Thanks in advance.