Subtracting and adding Time

I have setup a form to input a start time and finish time, but I need the values to remain in that format as supposed to 16:45 = 16:75. Could anyone please please tell me how I would subtract, for example, 08:45 from 16:15 to make 07:30!!
Read it a few times and you'll see what I mean!

This should work, the problem is, I don't know the correct interval code.

Code:

---

<%
  StartTime = TimeValue("08:15")
  EndTime = TimeValue("16:45")
  TimeDiff = DateDiff("h", StartTime, EndTime)
  Response.Write(TimeDiff)
%>

---

This will return 8. I've tried h:mm and just m, but I can't return 7:30.

Play around with it and see what you can do.

You can also do like this:

Code:

---

oldTime = Format("16:15", "hh:mm")
newTime = DateAdd("h", -8, oldTime)
newTime = DateAdd("n", -45, newTime)
MsgBox "If you substract 8h & 45m from 16:15 you get: " & Format(newTime, "hh:mm")

---

This gives you "07:30".

Note that "format" only works in VB not in ASP. An ASP ex. is:

Code:

---

<%
oldTime = "16:15"
newTime = DateAdd("h", -8, oldTime)
newTime = DateAdd("n", -45, newTime)
Response.Write("If you substract 8h & 45m from 16:15 you get: " &newTime)
%>

---

You can control the time format with "session.lcid" in ASP.

D'oh. That's it. N is minutes because M is month.

Anyway, there should be a way to use DateDiff with "h:nn", but I can't get it to work.