[help] how to change mobs drop rate :S

hi
can any one tell me how to change a mob items drop rate (at hamachi server)

and i have a problem with good vendor
that : in first kingdom the stones+5 are sold for 150kk and at the second kingdom sold for 50kk ... how i can fix this :confused::confused: ?? plz help me :D

at mobs drop is on filezilla /usr/rain/channel/share_data/locale/hongkong/quest
common_drop_item.txt
and
etc_drop_item.txt

if anyone know how i can change mobs yang drop no at navicat pleace tell me :/