Step-by-step explanation:
Applying the law of conservation of momentum,
Momentum before collision = Momentum after collision.



For an elastic collision,
Relative velocity of approach = Relative velocity of separation.


Using the value of
in equation (a)





Using the value of $v_{1}$ in equation (b)


Therefore the speed of truck after collision was found to be

And the speed of car after collision was found to be
