Vacation request and remaining vacation days

I urgently need to know the number of vacation days requested when a vacation request is submitted to the site manager by a blue-collar employee in order to make a decision. Remaining vacation days minus requested vacation days = vacation still available > the site manager wants to be able to make this decision quickly. Calculating this himself is inconvenient and takes too long, as he also has to check whether weekends or public holidays are included in the period.

It would also make sense to include this figure in the Personnel > "Requests" table.