Calculation in hours between date and time

Hi,

I have a table with logging moments for service calls. I use two measures to find the first start date

Date Time Created = CALCULATE(MIN(PBI_SER_Doc_ref_point[Date_Time_Registrated]);FILTER(PBI_SER_Doc_ref_point; PBI_SER_Doc_ref_point[Reference_Point]="8"))

and the date when the call is closed

Date Time Function Recovered = CALCULATE(MAX(PBI_SER_Doc_ref_point[Date_Time_Registrated]);FILTER(PBI_SER_Doc_ref_point; PBI_SER_Doc_ref_point[Reference_Point]="10"))

Now I want the caluclate the difference between those measures. But when I use a measure to calculate the difference I get an date as awnser. I want the total difference in hours. I also added an example of my table which I extract.

Call date