Converting date-time to date on a report display where date-time is the side effect of a formula subtracting days from a date

Converting date-time to date on a report display where date-time is the side effect of a formula subtracting days from a date

In some of my reports there are columns that look like this: "30-Oct-2017 12:30:00". I think the source of the time element is that I started out with  a pure date on a form and performed some date-arithmatic on it (subtracted 30 days etc.) using a formula in the form.

So the base column displays as a pure date but the derived columns display as date-time. 

Is there a way to fix this? To display (or fundamentally do the arithmetic) on dates instead of date-times?