Sub Worksheet_Change(ByVal Target As Range)
If Target.Count > 1 Then Exit Sub
If Not Intersect(Target, Range("C3,D3,C7")) Is Nothing Then
[C9] = "Ecart de " & [C6] & " dû à " & [C7]
NbCarVariation = Len([C6])
[C9].Characters(Start:=10, Length:=NbCarVariation).Font.Bold = True
[C9].Characters(Start:=10 + NbCarVariation + 7, Length:=Len([C9])).Font.Bold = True
End If
End Sub