public static int ValueOf(IBox box, string color) { var oneColorFlowers = box.GetFlowerList() .Where(x => x.GetFlowerColor().ToUpper() == color.ToUpper()) .ToList(); var priceList = PriceList.GetInstance(); int value = 0; foreach (var item in oneColorFlowers) { value += priceList.GetFlowerCharge(item); } return(value); }