private bool checkBuying(Buying buy)
 {
     return(buy != null && buy.Package.Any(it =>
                                           it.Drink > 500 ||
                                           it.Agriculture > 500 ||
                                           it.Factory > 500 ||
                                           it.Service > 500
                                           ));
 }
        private double CalcBuying(Buying buying)
        {
            var sum = ((buying?.Package?.Where(it => it != null).Sum(it => (it.Size ?? 0) * (it.Drink ?? 0) / (!string.IsNullOrEmpty(it.Name) && it.Name.Contains("ขวด") ? 1000 : 1))) ?? 0) * 12 / 100.0;

            return(sum);
        }