How to compute elapsed minutes in flash AS 1.0

Ahoy hoy!

I’m trying to solve an AS 1.0 elapsed minutes. In MS Excell this should be easy but i’m having a hard time in Flash MX. I have an equation such as this:

Start: 1/28/08 9:00 AM
End: 1/28/08 10:19 AM
Duration: 79 mins.

In Excell I can plot this easily such that if Start is in R23 and End is in R25 my equation would be:


and I get the 79 mins as a result.

Anyone can help me in AS 1.0?