In a map, the distance between two places is 5cm, which means the actual distance is 15km. What is the scale of this map

In a map, the distance between two places is 5cm, which means the actual distance is 15km. What is the scale of this map

As long as the distance on the map and the actual distance into the same unit and then divide it 15km = 1500000cm, then 5:1500000 = 1:300000, come on!