Time Math and Shifting - Please Help

[OSXMS]

Hi Everyone, I need to be able to evaluate two time cells (in MM:SS) format. Then take the result and change the time in another cell.

Basically this is for timing an event. Segment times are planned but run high or low depending on things. So I want to be able to say seg1, your time is 5:00. But if when done it was actually 5:15 - then change the segment time in Seg2 up or down automatically. The idea is that the show must always end with the same total time, even if the four segments vary.

How hard is this? I am not an excel guru by any means. Any help or expertise is very much appreciated.

[ChemistB]

I would upload a spreadsheet with an example of your layout (go Advanced>Manage Attachments). I envision columns A and B having your estimated times and Col D and E having your actual times (calculated using formulas)