Notam cu x lei suma initiala.
a) I zi: 2x/3 +15 lei
rest = x-2x/3 - 15
II zi : 2/5 ( x-2x/3-15)
III: 27 lei
restul = 3/5 ( x-2x/3 - 15) = 3/5 (( x-45)/3) = (x-45)/5 = 27
x-45 = 5*27
x-45 = 135
x= 180 lei
b) II zi : 2/5 ( 180 - 2*180/3 - 15) = 2/5 *45= 18 lei