LO Base calculating times

Is there a way in Base I can calculate the elapsed time between two fields stored as TIME; a StartTime and a FinishTime. If I try to run [FinishTime] - [StartTime] in my query, it appears to return a number that equals the elapsed seconds but I can’t seem to then format the result as HH:MM. Furthermore, if I try to divide the result by 1360, it seems to multiply instead of divide.

LibreOffice 6.1.3.2 Base on Windows 10 (x64)

What am I doing wrong?

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Attached screen grabs show the table structure and query results.

It would help if you can show the query you are using, with the table structure against which you are querying. Edit your question to add the information, or use a comment.