10b+10B=3000grame
5b=5B-500grame rezulta ca 10b=2(5B-500grame)=10B-1000 grame si inlocuim in prima ecuatie
10B-1000grame+10B=3000grame
20B=4000grame
B=200grame
acum aflam b tot din prima ecuatie
10b+10*200grame=3000grame
10b+2000gra,e=3000grame
10b=1000grame
b=100grame
3b+3B=3*100grame+3*200grame=300grame+600grame=900grame