????????
      +---------
XWMXQ | WTNHXHMW
       -QGWQW
        =====
        XXWTMH
       -XTQGNW
        ======
         XXTNGM
        -XTQGNW
         ======
           MGXHW
          -MHFAT
           =====
           ?????

base: 10
letters: AFGHMNQTWX
difficulty: medium