As per the question, the system consists of two cars.
The the masses of two cars are denoted as-
The two cars undergoes collision with each other. Here collision must be inelastic in nature.
Let the velocities of each car is denoted as-
It is given that masses of two cars and initial velocities-
First we have to calculate the total momentum of the system before collision.
The momentum of a body is the product of its mass with velocity.
Momentum of car 1:
The momentum of car 2:
Now the total momentum of the system is :
Now we are asked to calculate the total momentum of the system after collision.
The basic condition in case of any type of collision is that it is in accordance with law of conservation of linear momentum.
Hence, the momentum will be conserved here.
It means the total momentum before collision must be equal to the total momentum after collision.
Hence, the correct answer to the question will be 2400 kg m/s.