Metoda comparației
3 pixuri.....4 stilouri.....25, 50 RON | × 2
2 pixuri.....3 stilouri.....18, 50 RON | × 3
6 pixuri.....8 stilouri.....51 RON
6 pixuri......9 stilouri.....55, 5 RON
-----------......1 stilou......4, 5 RON
3 pixuri.....4 × 4, 5 = 18 RON.....25, 50 RON
3 pixuri.....25, 50 - 18 = 7, 5 RON
1 pix.....7, 5 : 3 = 2, 5 RON