using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var list = new List<Request>();     

        list.Add(new Request{ AccountId = 1, Name = "Yes", WantToTrade = true, PotentialTradeSupplies = new List<Supply>{ new Supply {CanBeTraded = true}, new Supply {CanBeTraded = false}, new Supply {CanBeTraded = false}}});

        list.Add(new Request{ AccountId = 2,Name = "No", WantToTrade = false, PotentialTradeSupplies = new List<Supply>{ new Supply {CanBeTraded = true}, new Supply {CanBeTraded = true}, new Supply {CanBeTraded = true}}});

        list.Add(new Request{ AccountId = 3,Name = "No", WantToTrade = true, PotentialTradeSupplies = new List<Supply>{ new Supply {CanBeTraded = false}, new Supply {CanBeTraded = false}, new Supply {CanBeTraded = false}}});

​

        var accountId = 1;

        var result = from supply in list

                where supply.AccountId == accountId 

                     && supply.WantToTrade && supply.PotentialTradeSupplies.Any(p=>p.CanBeTraded)

                select supply;

        Console.WriteLine("Count: " + result.Count());

        Console.WriteLine("Prints first from list above : " + result.First().Name + " " + result.First().AccountId);

    }

    class Request {

        public int AccountId {get;set;}

        public string Name {get;set;}

        public bool WantToTrade  {get;set;}

        public List<Supply> PotentialTradeSupplies  {get;set;}

    }

    class Supply {

        public bool CanBeTraded{ get;set; }

    }

}