Drachma and Denarius
1 Drachma was the daily wage of a skilled laborer (Greek Currency)
1 Denarius was the daily wage of an unskilled laborer (Roman Currency)
1 piece of silver (Tetradrachm) equaled 4 drachmas; thus, Judas' 30 tetradrachms equaled 120 drachmas or 4 months' (120 days') labor wages of a skilled laborer.
*According to Labor Dept of Delhi government, the minimum wages per day of a skilled laborer is Rs.423; of unskilled laborer, Rs.348, but could be higher than this minimum rate.