We are given
The scale model of a building is 5.4 ft tall of the original building is 810 meters tall
so, we get
5.4 ft = 810 meters
now, we can find for 1ft
so, we can divide both sides by 5.4


So, we got scale as
The scale model of a building is 1 ft tall of the original building is 150 meters tall.......Answer