EXAMPLE: For the equations:
      2X   + 3Y  + 4Z = 119
      5X   - 6Y   + 7Z =  80
      8X   +9Y   +10Z = 353

You would enter:
      Eqtn 1:     2   3   4   119
      Eqtn 2:     5   - 6   7     80
      Eqtn 3:     8   9   10   353

Click E N T E R for the answers:
          X=12 Y=13 Z=14