Formula for multiple entries

Hi,

i'm new to excel, and this is probably easy enough to solve, but i'm stumped.

I am creating a work book and i'm looking to add or subtract values from 3 columns into a separate column, the value in the column they are being entered into i need the total to remain, but i need to reset the other 3 columns back to zero after say 2 mins.

Is this possible???

Also i need to transfer data from a sage package into a excel document column, this is live data which is constantly updated??

Is this possible???

Thanks