Peter drives between two cities several times a year. The first half of the distance is limited to 60 km / h and the second half of the distance is limited to 80 km / h. Peter believes that if he instead keeps the speed 70km / h the entire distance, it will take as long as if he keeps speed limits. To his surprise, it turns out that it takes 3 minutes longer legally. How far is the distance between these two cities.