Hi,
Departure point : (4, 5)
They are first heading west, to go to the (2,5).
They made 2 km.
Then they are heading north, to go to (2,8) -> campsite.
They made 3 km
To return to departure point, the make the choice to walk in straight line :
In total : they walked : 2 + 3 + 3.60 = 8.60 km