notam c-pretul unui kg crap
s-pret un kg salau
75c.....42s......1389lei
25c.....50s......1075lei |×3
75c.....42s......1389lei
75c.....150s.....3225lei
--------------------------------- scadem pe prima din a doua
/.........108s......1836
108s=1836lei
s=1836:108
s=17lei (un kg salau)
inlocuim
25c+50·17=1075
25c+850=1075
25c=1075-850
25c=225
c=9 lei (kg crap)
verificam in prima relatie
75·9+42·17=675+714=1389
deci 1kg crap=9lei, 1kg salau=17 lei
