Final answer:
The average velocity of the man's car is 50 km/h.
Step-by-step explanation:
The average velocity can be calculated by dividing the total distance traveled by the time taken. In this case, the man traveled a distance of 25 km in 30 minutes. To find the average velocity, we divide 25 km by 0.5 hours (30 minutes converted to hours). The average velocity is therefore 50 km/h.