public ActionResult TipCalculator(TipCalculatorRequest request)
        {
            if (ModelState.IsValid)
            {
                var calc = new TipCalculator();

                // convert tip calculator model to tip calculation

                var tipData = new TipCalculation();
                tipData.MealTotal = request.MealTotal.Value;
                tipData.TipPercent = request.TipPercent.Value / 100;

                var result = calc.CalculateTip(tipData);
                return View("TipCalculatorResult", result);
            }
            else
            {
                return View(request);
            }
        }
 // tip calc
 public ActionResult TipCalculator()
 {
     var model = new TipCalculatorRequest();
     return View(model);
 }