Plastic bag cost= length*width*layers*thickness*proportion*price per kilogram.
For example: there is double layer 40cm length, 30cm width, 0.04mm
thickness PP material bag, the PP material price is 14600 RMB per
ton，the proportion is 0.91.
The bag cost =0.4*0.3*2*0.04*0.91*14.6=0.1275 RMB
Actually there will be some waste in real production, we normally set the propotion as 1.
Then the bag cost=0.4*0.3*2*0.04*1*14.6=0.14 RMB
On the other hand there will be The cost of utilities, staff salaries, pilot expenses, factory rent, equipment depreciation expense, sample expenses, etc., shall be equally amortized to each bag