Sub Test()
Dim F1 As Range
Dim i As Integer
Dim DernLigne As Long
DernLigne = Range("b" & Rows.Count).End(xlUp).Row
Set F1 = Sheets("Feuil1").Range("b2:b" & DernLigne)
Range("B2:C2").Select
Selection.AutoFilter
ActiveSheet.Range("B2:B" & DernLigne).AutoFilter Field:=1, Criteria1:="Avoir"
Range("B3").Select
For i = 2 To F1.Rows.Count
If F1(i, 1).Value = "Avoir" And F1(i, 2).Value > 0 Then
F1(i, 2).Value = F1(i, 2).Value * -1
End If
Next i
End Sub