How many kilometres will be travelled when the cars are level?

Question

Two cars set off form the same point to travel the same journey.

The first car has a start of seven minutes before the second car leaves.

If the first car travels at 60 kph and the second car travels at 90 kph,

how many kilometres will be travelled when the cars are level?

Answer 1

21 km.
The difference between the cars is 30 kph or 0.5 k/s
The head start of car one is 7 minutes at 60 pkh = 7 km
It will take 7 / 0.5 = 14 minutes to gap this distance.
Car 2 will then have traveled 14 min * 90 kph = 21 km.
Check: car 1 will have traveled 21 min * 60 kph = 21 km.