Răspuns :
II =B
III=C
IV=D
B+D=240
270-240=30 elevi (clasa a III)
B+C=120
B+30=120
B=120-30
B=90 elevi (clasa a II)
240-90=150 elevi (clasa a IV)
II+III+IV=270
II+IV=240
II+III=120
120+IV=270=>IV=270-120=>IV=150 elevi cls a4a
II+150=240=>II=240-150=>II=90 levi cls. a2a
90+III=120=>III=120-90=>III=30 elevi cls a3a
II+IV=240
II+III=120
120+IV=270=>IV=270-120=>IV=150 elevi cls a4a
II+150=240=>II=240-150=>II=90 levi cls. a2a
90+III=120=>III=120-90=>III=30 elevi cls a3a