Sum of 2 cells in a column equal a specific number

Let me know if this works for you:

Sub SumTwo()
    Dim numCnt As Variant, cl As Variant, xCnt As Long
    numCnt = Range("A1:A10").Cells.Count
    For Each cl In Sheets(1).Range("A1:A10")
        For xCnt = 1 To numCnt
            If cl.Value + cl.Offset(xCnt, 0).Value = 19 Then cl.Offset(xCnt, 2).Value = 19
        Next xCnt
    Next cl
End Sub