The momentum of the truck is approximately 22500 kg m/s.
Momentum or p is the product of an object's mass and velocity. In this case since we are given both the mass and velocity, we simply need to multiply to obtain the momentum.
mass = 750 kg
velocity = 30 m/s
p = mv
Substitute values.
p = 750 kg × 30 m/s
p = 22500 kg m/s