Public Class Form1
    ' tên label là
    ' tên của Listbox Danh là list_
    ' tên nút thoát là btn_thoat
    Private Sub btn_thoat_Click(sender As Object, e As EventArgs) Handles btn_thoat.Click
        If (MessageBox.Show("Bạn có muốn thoát?", "Thông báo", MessageBoxButtons.YesNo).Equals(DialogResult.Yes)) Then
            Application.Exit()
        End If
    End Sub

    Private Sub btn_lamlai_Click(sender As Object, e As EventArgs) Handles btn_lamlai.Click
        txt_a.Text = ""
        txt_b.Text = ""
        txt_c.Text = ""
        txt_ketqua.Text = ""
    End Sub

    Private Sub rad_ptbacnhat_CheckedChanged(sender As Object, e As EventArgs) Handles rad_ptbacnhat.CheckedChanged
        txt_c.Enabled = False

    End Sub

    Private Sub rad_ptbac2_CheckedChanged(sender As Object, e As EventArgs) Handles rad_ptbac2.CheckedChanged
        txt_c.Enabled = True
    End Sub

End Class