On a map with a scale of 1:300000, the distance between the two places is 18 cm; on a map with a scale of 1:200000, how many cm should it be?

On a map with a scale of 1:300000, the distance between the two places is 18 cm; on a map with a scale of 1:200000, how many cm should it be?

It's 18 △ 1 / 300000 × 1 / 2000000 = 2.7cm