Hi @Sevendust,
Could you please share a bit more about your scenario?
Do you want the End Date/Time to be equal to selected date (e.g. '10/25/2018 18:30 ') plus actual hours?
If you want the End Date/Time field to be equal to selected date (e.g. '10/25/2018 18:30 ') plus actual hours within your Edit form, I think the DateAdd function could achieve your needs.
I have made a test on my side, please take a try with the following workaround:
Set the Default property of the End Date Data card to following formula:
If(
IsBlank(Actual_x0020_Hours_DataCard2.Update),
Start_x0020_Date_DataCard2.Update,
DateAdd(Start_x0020_Date_DataCard2.Update,Actual_x0020_Hours_DataCard2.Update,Hours)
)
Note: The Start_x0020_Date_DataCard2 represents the Start Date Data card control, the Actual_x0020_Hours_DataCard2 represents the Actual Hours Data card control.
The GIF screenshot as below:
More details about the DateAdd function in PowerApps, please check the following article:
DateAdd function
Best regards,
Kris