????????
     +---------
REXU | FXEAUFJE
      -XJFRU
       =====
        JJRUF
       -JXRFU
        =====
         ERJFJ
        -EAXJU
         =====
          EERJE
         - REXU
          =====
          ?????

base: 7
letters: AEFJRUX
difficulty: intermediate