????????
      +---------
LRGJM | NHFTTMGT
       -LRGJM
        =====
        TUNJYM
       -MGUUWR
        ======
         RRTJJG
        -RPYYQJ
         ======
          YMRUTT
         - LRGJM
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: medium
missing: X