Notam x lei suma data.
luni : 1/2 x = 0,5x
restul = x- 0,5x = 0,5x
marti : 1/3 din rest= 1/3 ori 0,5x = 0,5x/3
rest = 0,5x-0,5x/3 = x/3
miercuri : 1/2 ori x/3 = x/6
rest : x/3 - x/6 = x/6
joi : 1/3 ori x/6 = x/ 18
rest final : x/6 - x/18 = 2x/18 = x/9
x/9 = 10 deci x= 90 lei