From city A to city B, the distance between which is 720 km, a car drove out. After 15 minutes, the second

From city A to city B, the distance between which is 720 km, a car drove out. After 15 minutes, the second car drove out from city B to city A at a speed 20 km / h less than the speed of the first. They met after 5 hours. Find the distance traveled by the second vehicle to the meeting.

1. The distance between the cities is: S = 720 km;

2. Speed of the second car: V2 km / h;

3. Speed of the first car: V1 = (V2 + 20) km / h;

4. The second car left later at: To = 0.25 hour;

5. Cars met in time: Tn = 5 hours;

6. Let’s compose the equation of motion:

S = V2 * Tn + V1 * (Tn + To);

720 = V2 * 5 + (V2 + 20) * (5 + 0.25) = V2 * 5 + (V2 + 20) * (5.25) =

10.25 * V2 + 105;

V2 = (720 – 105) / 10.25 = 60 km / h;

7. Path of the second car: S2 = V2 * Tn = 60 * 5 = 300 km.

Answer: before the meeting, the second car drove 300 km.