Răspuns:
2 ore jos --- 7 ore bic. --- 157 km l×3
3 ore jos --- 4 ore bic. --- 99 km l×2
6 ore jos --- 21 ore bic. --- 471 km
6 ore jos --- 8 ore bic. --- 198 km
avem
21-8= 13 ore
471-198= 273km (in 13 ore)
273:13= 21 km (1 oră)
21×4= 84 km bic. (in 4 ore)
99-84= 15 km jos (in 3 ore)
15:3= 5 km jos (1 oră)