Solve for any letter in any equation.

I'll arbitrarily choose to solve the middle equation for z.




Now substitute  for  in both
the other two equations:



so we get



Then we simplify:





Now we have it down to 2 equations and 2 unknowns

We solve the 2nd one here for x:




Then we substitute  for  in the
other equation:



becomes:



Then we solve for y:







Now we substitute  for y in
the equation above solved for x:
 





Finally we substitute  for y and
 for x in the equation above solved for z:









So the final solution is 

Edwin