Answer:
1 hour
Step-by-step explanation:
The second car will lap the first car when it has traveled a distance equal to the track length farther than the first car in the same time.
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The track length is 20 km, so the second car needs to travel 20 km farther than the first.
The difference in rates is 80 km/h -60 km/h = 20 km/h. This means the second car will travel 20 km farther than the first in each hour they race.
The second car will lap the first car after 1 hour.
