VIisualBasic.Net / Not Hesaplama

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim Not1, Not2, Not3, Ortalama As Integer
        Not1 = TextBox1.Text
        Not2 = TextBox2.Text
        Not3 = TextBox3.Text
        Ortalama = (Not1 + Not2 + Not3) / 3
        Label4.Text = Str(Ortalama)
        If Ortalama < 45 Then MsgBox("Dersten çaktın")
        If Ortalama > 44 Then MsgBox("Dersten Geçtin")
 
    End Sub