x-lungimea drumului
I zi: x-(20/100)·x=x-2x/10=(10x-2x)/10=8x/10
II zi: 8x/10-(30/100)·4x/5=8x/10-12x/50=(40x-12x)/50=28x/50
28x/50=560
28x=560·50
28x=28000
x=28000/28
x=1000 km
I zi a parcurs: 1000x20%=200 km
II zi a parcurs: (1000-200)x30%=240
III zi:100-200-240=560