Fast formula for Absence Rollover rule

Summary:

Content (required):

We have a requirement to configure Absence Rollover rule such that only the leftover balance above the allowed carry over limit should rollover to another plan.

For example, If a person is having 25 days of absence balance at the end of plan year, they should carryover 7 days of absence to next year and the remaining 18 days should roll over to another plan.

How can I achieve this using fast formula?

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):