Answer:
v = -24.5 m/s
Step-by-step explanation:
Use conservation of momentum P = m*v. Unless there are external forces involved, total momentum must be conserved.
P: momentum
m: mass
v: velocity
1. calculate the total momentum before the collision:

2. the total momentum after the collision must not change:

3. after the collision the velocity of the car is the same as the velocity of the truck:

4. combining 2. and 3.:

5. this equation only has one unknown and can be solved for v:

