Răspuns :
21 elevi b-baieti f-fete
f=b-3
f+b=21
b-3 +b =21
2b=24
b=12=>f=12-3=9
f=b-3
f+b=21
b-3 +b =21
2b=24
b=12=>f=12-3=9
fete /-----/
baieti /-----/ + 3 }21
21 - 3= 18
18 : 2 = 9
fete = 9
baieti = 9+3 = 12
9+12= 21
baieti /-----/ + 3 }21
21 - 3= 18
18 : 2 = 9
fete = 9
baieti = 9+3 = 12
9+12= 21