The distance between the two cities is 490 km. A passenger car drove out of one city at a speed of 90 km / h.

The distance between the two cities is 490 km. A passenger car drove out of one city at a speed of 90 km / h. After 1 hour and 30 minutes, a truck drove out from another city to meet her at a speed of 70 km / h. What is the distance between them in 1 hour 45 minutes after the truck leaves?

Let us express in hours the time of movement of cars on the way:
1 hour 30 minutes = 1.5 hours; 1 hour 45 minutes = 1.75 hours;
1) Determine the distance that the passenger car traveled independently in 1.5 hours: 90 • 1.5 = 135 (km);
2) Let’s find the distance that remains to be covered by both cars: 490 – 135 = 355 (km);
3) Find the total speed of cars: 90 + 70 = 160 (km / h);
4) Let’s calculate the distance that two cars will cover in 1.75 h: 160 • 1.75 = 280 (km);
5) Determine the remaining distance between cars in 1.75 hours: 355 – 280 = 75 (km).
Answer: there will be a distance of 75 km between cars in 1 hour 45 minutes.