Answer:
18.1 km
Step-by-step explanation:
The problem can be solved by resolving the vector representing the displacement into its components along the north-south and east-west directions.
Look at the figure below: the displacement is the vector that connects A (starting point) to B (ending point), while the distance covered during the return trip is the sum of the length of the two components along the north-south and east-west direction.
Using vector rules, we find the magnitude of the two components:
East-west:

North-south:

So the total distance covered during the return trip is
