Query 18. Export Total Sales by Customer

//Query 18. Export Total Sales by Customer
        public static string GetTotalSalesByCustomer(CarDealerContext context)
        {
            var customers = context
                .Customers
                .Where(c => c.Sales.Count > 0)
                .Select(c => new
                {
                    fullName = c.Name,
                    boughtCars = c.Sales.Count,
                    spentMoney = c.Sales.Sum(s => s.Car.PartCars.Sum(p => p.Part.Price))
                })
                .OrderByDescending(c => c.spentMoney)
                .ThenByDescending(c => c.boughtCars)
                .ToList();

            var json = JsonConvert.SerializeObject(customers, Formatting.Indented);

            return json;
        }