public sealed partial class Page2 : Page
    {
        public Page2()
        {
            this.InitializeComponent();
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            base.OnNavigatedTo(e);
        }

        private void PrevTotalBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            PrevTotalBox.Text = GlobalValueThree.total.ToString();
        }

        private void TipBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            int x = GlobalBusiness.select;
            int BusTip = 20;
            int PersTip = 15;
            if ( x == 1)
                {
                TipBox.Text = BusTip.ToString();
            }
            else
            {
                TipBox.Text = PersTip.ToString();
            }
        }
    }
}