lungime drumului = d
ziua 1 se parcurg 1/9 ·d = d/9 mai raman (rest) 8d/9
ziua 2 " " "" " " " " 0,25·8d/9 = 2d/9 " " " " " " " " " 8d/9 - 2d/9 = 6d/9 = 2d/3
ziua 3 " "" " "" "" 13/24·2d/3 = 13d/36 " " " " " " 2d/3 - 13d/36 = 11d/36 =55km
11d/36 = 55 d = 55·36/11 d = 180 km