7 gr. brad....12 gr. stejar.....750 kg /×2
3 gr. brad....8 gr. stejar......450 kg /×3
14 gr brad.......24 gr stejar......1500 kg
9 gr. brad.......24 gr stejar.......1350 kg
scadem cele doua relatii
5 gr. brad......150 kg
1 grinda brad =150:5=30 kg
7 grinzi de brad =7×30=210 kg
1 grinda stejar = (750-210):12 =540:12=45 kg