var list = new int[] { 10, 20, 30, 40, 45, 50 };
var result = list
  .Where(x => {
    Console.WriteLine("[Where] " + x);
    return x > 30;
  })
  .Select(x => {
    Console.WriteLine("[Select] " + x);
    return x * x;
  });

Console.WriteLine(string.Join(", ", result));