I need to know how to solve this problem cause I have a test tommorow. It's how to solve a system of not two, not three, but four linear equations. And for some reason the textbook doesn't show how to solve them. Care to help me out?

Solve the system of equations:

w+x+y+z=6

3w-x+y-z=-3

2w+2x-2y+z=4

2w-x-y+z=-4

if you know how to solve it can you just give me a brief step by step guide on how to. Thanks