3. Two cars are driving towards each other on the Kaluga - Moscow highway. The speed of the first car is 60 km/h, and the speed of the second car is $1 / 5$ more than that of the first. Before reaching a bridge 2 km long, which can only be crossed by one car at a time, the first car has 120 km left to travel, and the second car has 180 km left. Will the cars interfere with each other when crossing the bridge?
3. 4) $60: 5=12$ km/h - the second car is faster by this speed;
2) $60+12=72$ km/h - the speed of the second car;
3) $120: 60=2$ h - the time it takes for the first car to reach the bridge
4) $180: 72=2$ (remainder 36) h - the time it takes for the second car to reach the bridge
5) $60: 2=30$ km - the distance the first car will travel in half an hour;
6) 2 km $<30$ km - the first car will have enough time to cross the bridge.

Answer: they will not interfere.