Dim zap As String
    Dim st As String

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        zap = TextBox1.Text
        st = TextBox2.Text
        If st < 1 Then TextBox7.Text = 0 Else
        If st >= 1 And st < 5 Then TextBox7.Text = zap * 8 / 100 Else
        If st >= 5 And st < 10 Then TextBox7.Text = zap * 15 / 100 Else
        If st >= 10 Then TextBox7.Text = zap * 2 / 100


        TextBox4.Text = zap * Val(TextBox3.Text) / 100
        TextBox6.Text = zap * Val(TextBox4.Text) / 100
        TextBox8.Text = zap * 50 / 100
        TextBox9.Text = zap + Val(TextBox7.Text) + Val(TextBox4.Text) + Val(TextBox6.Text) - Val(TextBox8.Text)


    End Sub

    Private Sub TextBox6_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox6.TextChanged

    End Sub