Belajar Program VB.net

CODING :
Public Class Form1

    Private Sub BtnProses_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnProses.Click
        If JlhLembar.Text >= 200 Then
            HPL.text = 90
        Else
            HPL.Text = 100
            Totalharga.Text = HPL.Text * JlhLembar.Text
            If Totalharga.Text >= 500000 Then
                Discount.Text = 0.15 * Totalharga.Text
            Else
                Discount.Text = 0
            End If
            pembayaran.Text = Totalharga.Text - Discount.Text

        End If
    End Sub

    Private Sub BtnHapus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnHapus.Click
        JlhLembar.Text = ""
        HPL.Text = ""
        Totalharga.Text = ""
        Discount.Text = ""
        pembayaran.Text = ""
    End Sub

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