The car passed the first half of the way at a speed of 90, the second at a speed of 54. Find the average speed.

1. In order to find the average speed, you need to divide the length of the entire path by the total time.
Let’s denote by 1 (unit) – half of the track.
Then the time to overcome the first half was 1/90 hours.
And the time to overcome the second part is equal to 1/54 hours.
2. The length of the entire road is 1 + 1 = 2 conventional units.
The total time will be 1/90 + 1/54 = (3 + 5) / 270 = 8/270 = 4/135 hours.
Let’s find the average speed.
2 / (4/135) = 2 * 135/4 = 135/2 = 67.5 km / h.
Answer: The average speed is 67.5 km / h.