Answer:
the correct one is F’= 4500 N
Step-by-step explanation:
To solve this problem we must use Newton's second law 
 
where F₁ is the force of the barge F₁ = 3000N and the force of the tugboat is F ' 
 
 F '- F₁ = m a 
we substitute 
 F '- 3000 = m a 
 
the mass is always a positive quantity, therefore if we want the tug to pull the barge 
 F ’-3000> 0
 
when you check it, you respect the correct one is F’= 4500 N