Question

Din cei 25 de elevi ai clasei a V - a B 16 elevi joaca handball , 13 tenis iar 2 nu fac sport deloc . Cati elevi practica ambele sporturi?

Answer 1

25-2=23 elevi care fac sport
16+13=29
29-23=6
6:2=3
Proba= 16-3=13
13-3=10
13-10=3

Answer 2

h+t+2+x=25 elevi
h=16
t=13
2 nu fac sport
---------------------
cati fac si h si t ?

x=(16+13+2)-25
x=31-25
x=6 elevi fac si hambal si tenis

13-6=7 elevi joaca numai tenis
16-6=10 elevi fac doar hambal

t=7 elevi
h=10 elevi 
t si h=6 elevi 
2 elevi nu fac sport...=> 10+7+2+6=25 elevi