|--------------------------------------| → lungimea traseului
|-------|-------|-------|-------|-------|
|-------| → prima zi
|-------|-------|-------|-------|
|-------| → a doua zi
|-------|--------|-------|
|-------| → a treia zi
|-------|-------| → 6 km a patra zi
6 km : 2 = 3 km .
prima zi , a doua zi , a treia zi = 3 km .
3 + 3 + 3 + 6 = 6 + 9 = 15 km. ( lungimea traseului )
