distanta totala = d
se parcurg maii raman de parcurs (rest)
ziua 1 d/5 + 10km 4d/5 - 10
ziua 2 3/10 ·(4d/5 - 10) =6d/25 - 3 4d/5-10 - 6d/25 + 3 = 14d/25 - 7
ziua 3 2/7 ·(14d/25 - 7) +12 = 4d/25 +10 8d/25 - 7 - 4d/25 -10 =4d/25 - 17
ziua 4 4d/25 - 17 = 83
4d/25 = 100 d = 100·25/4 d = 625 km