Answer:
The mass of a person walking west at a speed of 0.8 m/s with a momentum of 52.0 kg•m/s west is 65 kg.
Step-by-step explanation:
 The linear momentum of a particle of mass m or body m that moves with a velocity v is defined as the product of mass by velocity 
P = m * v 
Where, as previously stated, 
- P = momentum
- m is the mass of the body
- v is the velocity.
 The units in the SI (International System) are N*s (
 )
)
 Then, the mass of a person, knowing the speed and momentum, can be calculated as:

In this case=

m= 65 kg
Then, the mass of a person walking west at a speed of 0.8 m/s with a momentum of 52.0 kg•m/s west is 65 kg.