Answer:
2 km south
Step-by-step explanation:
In order to calculate this you just have to have in mind that your starting point will be 0, and as south and north are contrary, one of the will benegative, in this case we will take south as negative, so lets begin:
-4 km south
+2 km north
-5 km south
+5 km north
This equals -2 km, since it is negative we know that it´s south, so the displacement after all will be 2 kilometers south from the starting point.