3 covrigi--------4 paini----------2300g x7
7cov.------------7paini------------4200g x3 4 paini-500x4=2000g
3 cov.-2300-2000=300g
21cov.---------28paini---------16100g 1cov.-300:3=100g
21cov.---------21paini---------12600g
\------------7paini---------3500g
1paine---------3500:7=500g