Here is the puzzle as it appeared in the AARP Magazine:

  1     +     2     +     3     =     X  
  4     +     5     +     6     =     N  
  7     +     8     +     9     =     ?  


Here are some additional clues from Mr. P:

  1     +     4     +     7     =     E  
  2     +     5     +     8     =     N  
  3     +     6     +     9     =     N  


            Send your solution by the end of the month to: David Pleacher