SAP BO - Time elapsed between first and last day of month (downtime)

Question

I want to calculate the total downtime of the machines between the first and the last day of the month.

My time measure is Stillstandzeit [h]

I have identified the:

• First day of last month: =RelativeDate(LastDayOfMonth( RelativeDate([Last day of Last Month];-45));+1)

• Last day of last month: =RelativeDate([First day of Current Month];-1)

And I want to find the hours in between.

Thanks a lot.

Ektor