var numbers = new ListThe Expr Block used in this case is `n => n % 2 == 0`. This block is passed to the `Where` method which filters out any odd numbers from the list. The resulting list is then used to calculate the average using the `Average` method. C# Expr Block is a part of the .NET Framework Class Library.{ 1, 2, 3, 4, 5 }; var average = numbers.Where(n => n % 2 == 0) .Average();