Macro formula help

NLepley 

If you prefer VBA code:

Right-click the sheet tab.

Select 'View Code' from the context menu.

Copy the code listed below into the worksheet module.

Switch back to Excel.

Save the workbook as a macro-enabled workbook (.xlsm)

Make sure that you allow macros when you open it.

Private Sub Worksheet_Change(ByVal Target As Range)
    Const Interval1 = 15
    Const Interval2 = 35
    Const Interval3 = 110
    Dim rng As Range
    Dim dtm As Date
    If Not Intersect(Range("B2:B" & Rows.Count), Target) Is Nothing Then
        Application.ScreenUpdating = False
        Application.EnableEvents = False
        For Each rng In Intersect(Range("B2:B" & Rows.Count), Target)
            If rng.Value = "" Or Not IsDate(rng.Value) Or rng.Offset(0, -1).Value = "" Then
                rng.Offset(0, 1).Resize(1, 3).ClearContents
            Else
                dtm = rng.Value
                rng.Offset(0, 1).Resize(1, 3).Value = _
                    Array(dtm + Interval1, dtm + Interval2, dtm + Interval3)
            End If
        Next rng
        Application.EnableEvents = True
        Application.ScreenUpdating = True
    End If
End Sub