C# Online Compiler | .NET Fiddle

using System;
using System.Collections.Generic;
using System.Linq;
					
public class Program
{
	public class Student
	{
		public string First { get; set; }
		public string Last { get; set; }
		public int ID { get; set; }
		public List<int> Scores;
	}
	
	
	public static void Main()
	{
		List<Student> students = new List<Student>
		{
		   new Student {First="Svetlana", Last="Omelchenko", ID=111, Scores= new List<int> {97, 92, 81, 60}},
		   new Student {First="Claire", Last="O'Donnell", ID=112, Scores= new List<int> {75, 84, 91, 39}},
		   new Student {First="Sven", Last="Mortensen", ID=113, Scores= new List<int> {88, 94, 65, 91}},
		   new Student {First="Cesar", Last="Garcia", ID=114, Scores= new List<int> {97, 89, 85, 82}},
		   new Student {First="Debra", Last="Garcia", ID=115, Scores= new List<int> {35, 72, 91, 70}},
		   new Student {First="Fadi", Last="Fakhouri", ID=116, Scores= new List<int> {99, 86, 90, 94}},
		   new Student {First="Hanying", Last="Feng", ID=117, Scores= new List<int> {93, 92, 80, 87}},
		   new Student {First="Hugo", Last="Garcia", ID=118, Scores= new List<int> {92, 90, 83, 78}},
		   new Student {First="Lance", Last="Tucker", ID=119, Scores= new List<int> {68, 79, 88, 92}},
		   new Student {First="Terry", Last="Adams", ID=120, Scores= new List<int> {99, 82, 81, 79}},
		   new Student {First="Eugene", Last="Zabokritski", ID=121, Scores= new List<int> {96, 85, 91, 60}},
		   new Student {First="Michael", Last="Tucker", ID=122, Scores= new List<int> {94, 92, 91, 91} }
		};
		

		var query1 = from a in students
			where a.Scores.Average() >= 80
			&& a.First.Contains("a")
			&& a.Last.EndsWith("r")
			select a;
		
		Console.WriteLine("query1 result count: {0}", query1.Count());
		
		var query2 = students.Where(x=>x.Scores.Average() >= 80
										&& x.First.Contains("a")
										&& x.Last.EndsWith("r"));
		
		
		Console.WriteLine("query2 result count: {0}", query2.Count());
	}
}

 
using System;
using System.Collections.Generic;
using System.Linq;
                    
public class Program
{
    public class Student
    {
        public string First { get; set; }
        public string Last { get; set; }
        public int ID { get; set; }
        public List<int> Scores;
    }
    
    
    public static void Main()
    {
        List<Student> students = new List<Student>
        {
           new Student {First="Svetlana", Last="Omelchenko", ID=111, Scores= new List<int> {97, 92, 81, 60}},
           new Student {First="Claire", Last="O'Donnell", ID=112, Scores= new List<int> {75, 84, 91, 39}},
           new Student {First="Sven", Last="Mortensen", ID=113, Scores= new List<int> {88, 94, 65, 91}},
           new Student {First="Cesar", Last="Garcia", ID=114, Scores= new List<int> {97, 89, 85, 82}},
           new Student {First="Debra", Last="Garcia", ID=115, Scores= new List<int> {35, 72, 91, 70}},

Cached Result

query1 result count: 2
query2 result count: 2