I need to extract a data validated cell content and use it as a part of a new formula

Question

I would like to give the user the option to choose between DAYS360() and NETWORKDAYS().
For that, I thought about adding these 2 to a data validation cell.

Afterwards, I would like to be able to add that choice as part of a new formula that calculates the worked days as such:

=DAYS360(D12,E12)

Can that be accomplished within Google Sheets without scripts?
I've tried myself some formulas, but couldn't get to any solution.

Answer 1

Create a drop-down list with the values elapsed calendar days and working days in cell A12. Then use this formula:

=ifs(
  A12 = "elapsed calendar days", days360(D12, E12), 
  A12 = "working days", networkdays(D12, E12), 
  true, iferror(1/0) 
)