Question

Cristi si ovidiu au 18 baloane.Daca Ovidiu ii da lui Cristi 4 baloane,cei doi vor avea acelasi numar de baloane.Cate baloane are fiecare?

Answer 1

c+o=18
o-4=c+4
o=c+4+4
o=c+8

c+c+8=18
2c=18-8
2c=10
c=5

o=5+8=13