prima zi chelt x pe 2 rest =xpe 2
a doua zi chelt x/2 *1/3=x/6 total x/2+x/6 =2x/3 rest =x/3
a treia zi chelt x/3*1/2 =x/6 total 2x/3+x/6=5x/6 rest x/6
a patra zi x/6*1/3=x/18 total 5x/6+x/18=8x/9 inseamna ca nu a cheltuit x/9 sau 12 lei x=9*12=108