The force that the car applies on the truck will be 6000 N in the reverse direction.
As per the information provided, the car's mass is one-fourth that of the truck
The truck exerts a force of 6000 N onto the car
We aim to determine the force that the car exerts on the truck
According to Newton's third law, every action has an equal and opposite reaction
Hence, the force from the car on the truck is 6000 N in the opposite direction