alegem o variabila x
in prima plasa alba si in plasa neagra avem x bile
in plasa alba 2:x+1
in plasa alba 3:x+2
4:x+3
5:x+4
6:x+5
7:x+6
stim ca daca adunam nr de mingi obtinem 189:
x+x+x+1+x+2+x+3+x+4+x+5+x+6=189
8x+21=189
8x=168
x=168/8
x=21 bile in plasa neagra
21 bile in prima plasa alba
apoi...22,23,24,25,26,27