PowerPoint Macro to set width and X-offset of a Text Box

Sub SetTextBoxWidth()
'
'
    With ActiveWindow.Selection.ShapeRange
        .Fill.Transparency = 0#
        .Width = 668.75
        .Left = 25.5
    End With
End Sub

"Width = 668.75" corresponds to 23.6 cm, and "Left = 25.5" corresponds to 0.9 cm. 
One centimeter is equivalent to approximately 28.333333.