Question

PENTRU 4 ACADELE si 3 ciocolate, mama a platit 20 lei , in alta zi a cumparat 4 acadele si 5 ciocolate si a platit 28 lei Cat costa o acadea dar o ciocolata?
Multumesc si 64p

Answer 1

{4a+3c=20
{4a+5c=28 |×(-1)

{4a+3c=20
-4a-5c=-28

4a-4a+3c-5c=20-28
0-2c=-8
-2c=-8 |:(-2)
c=4
4a+3c=20
4a+3×4=20
4a+12=20
4a=20-12
4a=8
a=8:4
a=2

Answer 2

4a..............5c......28
4a.............3c.......20
---------------------------------
/                  2c=8=>c=8:2=>c=4 lei costa o ciocolata

4a+5x4=28
4a=28-20=>a=8:4=>a=2 lei costa o acadea