3 covrigi..........4 paini.......2300 grame /×7
7 covrigi..........7 paini........4200 grame /×3
21 covrigi.........28 paini.......161.000 grame
21 covrigi..........21 paini.........126.000 grame
4 paini= 500× 4=2000 grame
3 covrigi=2300-200=300 grame
1 covrig=300:3=100grame ( un covrig)