Question

afla pretul urmatoarelor produse dintr un magazin;6sticle de suc si 4 sticle de apa costa 38 lei 2 sticle de suc si 4 sticle de apa costa 18 lei

Answer 1

vom nota apa cu x si sucul cu y
6y+4x=38
2y+4x=18
daca le scadem obtinem 4y  38-18=20
deci 4y=20si y=20:4=5
si x =(2y+3x)-2y=4x deci 18-10=8
4x=8si x=8:4=2
deci apa=2 lei si sucul =5lei

Answer 2

6 sticle suc ....4 sticle apa....38 lei
2 sticle suc.....4 sticle apa ....18 lei 
___________________________
6-2=4(sticle suc in plus)
38-18=20(lei in plus)
4 sticle suc = 20 lei
20:4=5(lei o sticla de suc)
5x6=30 (lei 6 sticle suc )
38-30=8(lei 4 sticle apa )
8:4=2(lei o sticla de apa)          P:5x6+4x2=30+8
                                                   =38