Notam cu D=drum,
/ =supra
In prima zi : D:4=D/4
A doua zi: (D-D:4) /3=3D/12
A treia zi:1/2( D-D/4-3D/12)=1/2(12D-3D-3D)/12=1/2X6D/12=D/4
A patra zi: 30
D=D/4+3D/12+D/4+30
Numitor comun 12
12D=3D+3D+3D+30X12
12D=9D+360
12D-9D=360
3D=360
D=360:3
D=120 KM are drumul
