Get different

I am using this fantastic plugin for an intoxication form but there’s one thing that seems impossible to do: show 3 different results based on the results of an equation. I want to show a picture (green light) if the result of the equation lower than a particular number, another one if above a certain result and another one if it is between the two set results.

I am basically trying to write something like this in the dependencies area of the “Calculated Field”:
-if value<20 : then show this image
-if value>40: then show this other image
-If 20<value<40: other pic. But it doesn’t work ??

Anyone could please help?

Thanks a lot!