Question

please tell me the answer

Answer 1

see it is quite easy.
in the first case the force exerted by two is more that's why the trolley will cover more distance.
but in 2nd case trolley is moved by a single person that's why the force applied will be less and theirfore the distance would also be less.
in 3rd case trolley is moved in both directions that's why the forces are equal but opposite to each other. theirfore the trolley will not move .

hope this helps you.
marking the answer brainleast would be appreciated ^_^