public IHttpActionResult Purchase(decimal amount, int itemNumber) { if (DrinkRepository.RequestPurchase(amount, itemNumber) == true) { if (DrinkRepository._drinks.FirstOrDefault(d => d.Id == itemNumber).Quantity > 0) { return(Ok(DrinkRepository.MakePurchase(amount, itemNumber))); } } if (DrinkRepository._drinks.FirstOrDefault(d => d.Id == itemNumber).Quantity == 0) { return(new System.Web.Http.Results.ResponseMessageResult( Request.CreateErrorResponse( (HttpStatusCode)422, new HttpError("SOLD OUT!!!") ) )); } decimal remaining = DrinkRepository._drinks.FirstOrDefault(d => d.Id == itemNumber).Price - amount; return(new System.Web.Http.Results.ResponseMessageResult( Request.CreateErrorResponse( (HttpStatusCode)422, new HttpError("Please Deposit " + remaining) ) )); }