Answer:
15,000 N
Step-by-step explanation:
In order to calculate the force tension between the coupling of the car engine and the middle car, you have to remember the formula:

Now you need to remember that eventhoug the middle car weighs only 2000kg it is also carrying the weight of the caboose car, so the total weight 3000 kg, so you now insert the values into the formula:


So the force that the coupling is facing is 15,000 N.