Answer: 420km
Explanation:
So let us start by stating the obvious, a car has travelled 180 km in 3 hrs.
So:
3h = 180km
now double both sides:
6h = 360km
now let us find 1h by dividing 3h = 180km by 3:
1h = 60km
now we can add 6h = 360km and 1h = 60km which gives us:
7h = 420 km
:-)