Another car drove past the car, moving at a speed of 72 km / h. After 10 seconds, the distance between

Another car drove past the car, moving at a speed of 72 km / h. After 10 seconds, the distance between the cars became 100 m. At what speed was the second car moving?

Let’s find the speed of the second car relative to the first one:
100: 10 = 10 m / s
Since the speed of the first car, expressed in meters per second, will be equal to:
72000/3600 = 20 m / s. , then the own speed of the second will be equal to:
20 + 10 = 30 m / s = 30 * 3600 = 108 km / h.