subtracting minutes

[niyrho]

How do I subtract minutes from a formula? So if I have 1:30 pm in one cell how do I get it to subtract 30 minutes and put it in another cell.

I have to do it this way because the times will change day to day but the formula stays the same.

I just can't figure out how to tell it to subtract "minutes". The rest of it I think I can get.

 

[barry houdini]

To subtract 30 minutes from a time value in A1

=A1-"0:30"

 

[niyrho]

No wonder I couldn't get it. They made it too simple, lol.
Thanks