Aquino drives his skidoo 7 kilometers north.
he stops for luch and then drives 5 kilometers south the 7 kilometers north what was his displacement?

If I understand your question correctly, the displacement should be 2 kilometers north since he went north 7km and back 5km south resulting in a net change of 2km

this is different than distance which is total amount moved instead of net amount moved.  (in this case the distance would be 12km)