Acart is set up as shown below, with three fans directed to the left and two of the fans running. the motion of the cart is represented by the v vs t graph shown. if the experiment were repeated with all three fans running, what might the resulting v vs t graph look like?

The force of 3 fans would be grater than the force of 2 fans. 
So the cart would have greater acceleration to the right, and
it would reach a greater speed to the right.  The resulting
'v' vs 't' graph would have a greater positive slope, and would
be higher at any given time.

You might get a better answer if you let us actually SEE the
picture and the graph.

10 neutrons is the answer