8.1. A bus with programmers left Novosibirsk for Pavlodar. When it had traveled 70 km, Pavel Viktorovich set off from Novosibirsk in a car along the same route, and caught up with the programmers in Karasuk. After that, Pavel drove another 40 km, while the bus traveled only 20 km in the same time. Find the distance from Novosibirsk to Karasuk, given that both the car and the bus traveled at constant speeds.
Solution. Since by the time the car has traveled 40 km, the bus has traveled half that distance, its speed is exactly half the speed of the car. However, when the bus has traveled 70 km after the car's departure, the car will have traveled 140 km and will just catch up with the bus. According to the problem, this happened in Karasuk, so 140 km is the answer.

Criteria. Only the answer -1 point.

Answer with verification (for example, for specific speeds) - 2 points. Proven that the car's speed is twice the speed of the bus - 3 points.