The polar explorer walked 15 km on ice to the North Pole in a day. During this time, the ice was carried

The polar explorer walked 15 km on ice to the North Pole in a day. During this time, the ice was carried by the current to the south for 12 km. How much has the polar explorer actually moved to the North Pole in a day?

Since the north and south directions are completely opposite to each other, then, in this case, provided that the polar explorer moved exactly to the north and covered 15 kilometers, in reality he traveled a distance that would be equal to the difference between the polar explorer’s path to the north and the distance to which the ice was carried flow. In this case, we get.
15-12 = 3 kilometers.
This is due to the fact that the ice was moving in the opposite direction.
Answer. In fact, the polar explorer walked 3 kilometers to the North Pole.