When you add any object on a scaled drawing like a floor plan or landscape design, you can get precise placement using coordinates.
To see where an object is on the page first, click on it and you'll notice the coordinates appear at the bottom of your workspace.
If you need something to be at a precise location, instead of eyeballing it or guesstimating, you can double-click on the coordinates at the bottom of the page and enter your own Left and Top values.