How can I search for tasks *NOT* modified within n days?

I’m trying to set up a saved search that will show me tasks that have not been modified in a while.

I want to avoid my client’s questions not being responded to or acknowledged. I don’t see how to use the search to look for things that are getting stale, but rather only things that have been modified recently.

7 posts were merged into an existing topic: Would like ability to easily filter for stale tasks (not modified with last N days)