Task: Reasoning / Mathematical Reasoning
User instruction:
A car plans to take a 50-km highway, but due to heavy traffic it can only travel at 30 km/h. There’s an alternative national road to the same destination that is 60 km long, but it has 10 traffic lights where you must stop for 2 minutes at each one. To arrive faster than via the highway, what average speed (in km/h) must the car maintain on the stretches of the national road if it isn’t stopped at lights in order?

Evaluation criteria:
You must arrive at the correct answer.  
   - Correct answer: at least 45 km/h
The following information must be properly used in the reasoning process.  
   - Total waiting time at traffic lights is 20 minutes.  
   - To be faster than taking the highway, the trip must be completed within 1 hour and 20 minutes, excluding traffic-light waits.