Răspuns :
f=nr fete
b=nr baieti
f,b-nec
f+b=28
b=f/3
f=3b
3b+b=28
4b=28
b=28:4
b=7
f=3b=3*7=21
b=nr baieti
f,b-nec
f+b=28
b=f/3
f=3b
3b+b=28
4b=28
b=28:4
b=7
f=3b=3*7=21