x-nr banci
y- nr elevi
Daca ar sta 2 in banca, 2 ar ramane in picioare :
2x+2=y
Daca ar sta 3 in banca intr-o banca ar sta 2 si 4 banci ar fi libere:
3(x-4)-1=y
2x+2=y
3(x-4)-1=y
2x+2=3(x-4)-1
2x+2=3x-12-1
2+13=x
x=15 (banci)
y=2x+2=2*15+2=32 (elevi)