a=lungime drum
/=supra
Prima zi: a/4
A doua zi: 2/3(a-a/4)=2/3x3a/4=a/2
A treia zi: 1/2(a-a/4-a/2)=1/2(4a-a-2a)/4=1/2xa/4=a/8
A patra zi:60 km
a=a/4+a/2+a/8+60
8a=2a+4a+a+480
8a=7a+480
8a-7a=480
a=480 km este lungimea drumului
kilometri parcursi
Prima zi:a/4=480/4=120 km
A doua zi: a/2=480/2=240 km
A treia zi: a/8=480/8=60 km
A patra zi: 60 km
120+240+60+60=480 km