This is a very Access specific question. It is well off topic for an Excel
VBA group. I would suggest you ask it on an Access forum.

In principle, I would expect that you could append something to the end of the
macro which

Divides one control by another
Sets the background color of the relevant control according to the result.

This is if you are using controls on a form. If you are opening and viewing
the query directly I do not think it will be possible to apply a conditional
format.