Pick a letter and an equation to solve for it in.

I will pick z and the second equation to solve for z in:




Substitute  for z in the other two
equations, (but not the same one you just used) 

Substituting it in







Substituting it in








Now you just have this simple system:



and I'll bet you can finish that by yourself, just by
substituting back

Answer x=2, y=1, z=-1 

Edwin