Question

Un caiet si o linie costa 13 lei.Stiind ca 2 caiete si 3 linii costa 30 de lei,afla cat costa fiecare obiect.(metoda inlocuirii)

Answer 1

c+l=13, l=13-c
2c+3l=30
2c+3(13-c)=30
2c+39-3c=30
c=9, l=4

Answer 2

1c+1l=13 lei
2c+2c=13x2=26

2c+3l-2c-2c=30-26
l=4 lei
13-4=9 lei costa caietul'
4 lei costa linia