Maria wants to know the distance between the building and the tree. There is a pond near the building so Maria cannot measure the distance directly. Maria stands in front of the building with the tree in front of her such that, in her eyes, the top of the tree overlaps the top of the building. The building is 60 ft tall and the tree is 18 ft tall. The distance between the Maria and the tree is 20 ft. How far is it from the tree to the building?