Question

La un market o persoana cumpara 14 kg banane si 8 kg portocale costa 86 lei,iar 22 kg banane si 24 kg portocale costa 158 lei. Cat costa 3 kg banane si 1 kg portocale?

Answer 1

b-kg banane
p-kg portocale
14b+8p=86lei
22b+24p=158
Simplifici totul cu 2 si obtii:
 $\left \{ {{7b+4p=43| ori 3 \atop {11b+12p=79| ori (-1)}} \right.$
$\left \{ {{21b+12p=129} \atop {-11b-12p= -79} \right.$
10b / =50 -----> b=5lei 

7b+4p=43
7ori 5 +4p=43
35+4p=43
4p=8
p=2lei

3b+p=3ori5+2=17lei