x-suma initiala
I zi: x-x/5=(5x-x)/5=4x/5
II zi: 4x/5-1/4·4x/5=4x/5-x/5=3x/5
III zi: 3x/5-1/3·3x/5=3x/5-x/5=2x/5
IV zi: 2x/5-1/2·2x/5=2x/5-x/5=x/5
x/5=3000
x=3000·5
x=15.000 lei
I zi : 15000·1/5=3000 lei
II zi (15000-3000)x1/4=12000/4=3000
III zi: (12000-3000)·1/3=9000/3=3000
IV zi (9000-3000)·1/2=6000/2=3000
V zi: 3000
3000+3000+3000+3000+3000=15000·