Question

A girl and boy pull in opposite directions on a stuffed animal. The girl exerts a force of 3.5 N. The mass of the stuffed animal is 0.2 kg, and it is accelerating to the right 2.5 m/s2. What is the force that the boy is exerting?

Answer 1

The resultant force on the animal = Resultant mass * total acceleration 
F = 0.2 * 2.5 to the right
F = 0.5 to the right.

As, girl exerting a force of 3.5 N & it's not mentioned that she is in right or left, so the force exerting by boy would be either:
3.5-0.5 = 3  OR  3.5+0.5 = 4

If boy exerting a greater force then, answer will be 4 N & if girl exerting a greater force the, answer will be 3 N

Hope this helps!

Answer 2

The correct answer is 4. 

2.5 x .2 = .5

3.5N + .5N = 4N