Answer:
John mowing the lawn and Dan cleaning the room.
Step-by-step explanation:
The law of comparative advantage emphasizes on a country or individual to concentrate in what he/she has comparative advantage in doing. To benefit both John and Dan, since John has a comparative advantage in lawn mowing, he should concentrate on mowing the lawn while Dan concentrates on cleaning the room. This way, a lot of time and effort will be saved on both side.