Question

four children pull on the same stuffed toy at the same time , yet there is no net force on the toy.how is this possible?

Answer 1

If you and I were playing " tug-a-war " and we both pull on opposite sides with the same amount of force no one would move, the rope would be still, because the same force is on both sides of it.

Answer 2

There was no net force on the stuffed toy, because the kids might have the same strength,  The same force is on both sides of it.  They cancel each other out. They exert a force on the stuffed toy equal in strength but opposite in direction. The forces are balanced and the stuffed toy does not move.  Its like a game of tug-o-war, but you and I have the same strength. the rope would be still and not moving.