Hello,
if yo uare asking about the cost of idling in a month;
24 working days in a month, 50 min idling in a day means ; 1200 min. idling total. if 60 min idling takes 0,6 liters, 1200 min will take 12 liters. multiplying with 0,92, it will cost for a month as 11,04 dollars.
Hope to hear from you
Oguz