I am using opportunities in Salesforce to track professional services engagements.
As soon as the opportunity is won and closed, I will fill in a custom field called "number of days" which represents the number of man-days sold for the given opportunity e.g. 100.
I now use events inside the opportunity to track the engagement with the customer. I can have several events that may last from 1 day and up.
Can I sum the # of days in all the events and can I subtract that number from the custom field in the opportunity?
I am using the standard event object that is part of the opportunity by default (when creating an activity).