Two cars start moving towards each other when they are 45 kms apart. The first car moves at a speed of 40 m/s and the second one at 50 m/s. after how much time do they meet?

Correct option is B

Speed of the first car = 40 m/s = 40/1000 km/s = 0.04 km/s
Speed of the second car = 50 m/s = 50/1000 km/s = 0.05 km/s
Since the cars are moving towards each other, their speeds add up.
Relative speed = 0.04 km/s + 0.05 km/s = 0.09 km/s
Time = Distance / Relative speed
Time = 45 km / 0.09 km/s = 500 seconds