DAX for addition and division

hrlope 

I am not sure how your datamodel is setup but please try the following measure:

VAR _TimeOff =
    CALCULATE (
        SUM ( Append1[Time Off(Hours)]),
        FILTER ( Append1, MONTH ( Append1[Reported Date] ) = 10 )
    )
VAR _HoursReported =
    CALCULATE (
        SUM ( Append1[Hours Reported] ),
        FILTER ( Append1, MONTH ( Append1[Reported Date] ) = 10 )
    )
VAR _TicketCount =
    CALCULATE (
        DISTINCTCOUNT ( Append1[Number] ),
        FILTER (
            Append1,
            Append1[Assignment group]
                IN {
                    "DC - US - DDC - Hardware",
                    "DC - US - EDC - Hardware",
                    "DC - US - Impl and Maint DNG/EGV",
                    "DC - US - Planners"
                }
                    && MONTH ( Append1[Created] ) = 10
        )
    )
RETURN
    DIVIDE ( _HoursReported  + _TimeOff, _TicketCount, 0 )