Running comparison on Datediff with modified format.

Good evening and salutations!

I have a form that runs time calculations for me which works wonderfully. I would like to be able to run comparisons on those times.

The code that runs the times is as follows:

So it will return the difference between two times as hh:mm.

I would like to be able to compare the minutes. For instance:

If :mm >20 then txtbox = "suckaroony"

Thanks!