Answer: The quad will overtake the motorcycle on its $10-\mathrm{th}$ lap while the quad is on its 11-th lap.
2. A motorcycle and a quad bike are driving on a circular road, a quarter of which passes through a forest, and the remaining part - through a field. The motorcycle's speed when driving through the forest is 20 km/h, and through the field - 60 km/h. The quad bike's speed when driving through the forest is 40 km/h, and through the field - 45 km/h. The quad bike and the motorcycle enter the forest at the same time. Which of the vehicles will overtake the other first, and on which lap will this happen?