Convert from arratel, artel [Arab] to kwan [Japan]

Unit Definition (arratel, artel [Arab])
The arratel is a versions of a traditional Arab unit of weight; see rotl. The spelling "arratel" is used in Portugal as an alternate name for the libra.

Unit Definition (kwan [Japan])
The kwan is a traditional Japanese unit of weight equal to 6.25 kin, which is about 8.27 pounds or 3.75 kilograms.