Calculating DataDiff in Workingdays with blank values

v-lionel-msft thanks for your help.

The 2 tables have a relationship based on Date (in the Date Table) and de date in the column 'Binnenkomst' (in the Damage table)

The damage table consists of addresses and dates when a damage is registrered (column 'Binnenkomst') and when it's solved (column 'Afgehandeld')but also a damage type and category.
The Date table consists of Date, weekday, isWorkday, DayOfWeek and Week number

Adres           Binnenkomst           Afgehandeld          Calculated column

A                  01-03-19                 03-03-19                Date Afgehandeld - Date Binnenkomst

B                  15-08-19             

C                  31-10-19                 01-11-19

D                  16-05-18                 16-08-18 

E                   06-12-19

Basically it needs to calculate that IF afgehandeld = BLANK() then calculated as if Afgehandeld is TODAY() and still returns an value based on workingdays