Answer:
Mark must push stronger.
Explanation:
The heavier box is being pushed downwards with higher force, due to earth's gravity. Since it is more "attached", or shall we say, attracted, to the ground, the force needed to make it move and overcome the friction between the bottom of the box and the floor will be higher.
In the other hand, Joey's box is being attracted to the ground with lesser force, he will need lesser force to overcome the friction and make it move.
Hope it helped,
BiologiaMagister
