Setting Excel cell value based on another cell value using VBA

I have the following spreadsheet. When ever there is an x in cell B I need to populate the d and e cells in the same row using an equation I have. if there is no x in the b cell I need to manually enter values into cells d & e.

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How do I make my code non-row specific?

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim val As String
    val = Range("B3").Value
    If val = "x" Then
        Range("E3").Value = Range("d2").Value * Range("G2").Value
        Range("D3").Value = Range("D2").Value
    End If
End Sub


I'm not sure if I understand correctly, but if you have a parameter: row = 3 you can use Range("E" & row) instead of Range("E3").

Put a loop around that where you vary 'row' for the rows you want to modify.

Hope that helps!