simple shopping cart in vb

gistfile1.txt

Public Class Form1

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click

    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        Const LX As Integer = 100
        Const BN As Integer = 500
        Const SD As Integer = 200
        Const HD As Integer = 80
        Const HM As Integer = 300
        Const AM As Integer = 160
        Dim sum As Integer

        If CheckBox1.Checked = True Then
            sum += LX
        End If
        If CheckBox2.Checked = True Then
            sum += BN

        End If
        If CheckBox3.Checked = True Then
            sum += SD
        End If
        If CheckBox4.Checked = True Then
            sum += HD
        End If
        If CheckBox5.Checked = True Then
            sum += HM
        End If
        If CheckBox6.Checked = True Then
            sum += AM
        End If
        TextBox1.Text = sum.ToString("c")

    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub

    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
    End Sub
End Class

I used Microsoft visual basic 2010 express to write the code.
And it was part of my assignment