how te merge elements with linq if id is the same in csharp

main.cs
class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

// example list of persons
List<Person> persons = new List<Person>()
{
    new Person() { Id = 1, Name = "John", Age = 25 },
    new Person() { Id = 2, Name = "Jane", Age = 30 },
    new Person() { Id = 1, Name = "Jack", Age = 35 }
};

// group persons by id and merge with Select
var mergedPersons = persons
    .GroupBy(p => p.Id)
    .Select(g => new Person()
    {
        Id = g.Key,
        Name = string.Join(", ", g.Select(p => p.Name)),
        Age = g.Sum(p => p.Age)
    });

// iterate over the merged persons
foreach (var person in mergedPersons)
{
    Console.WriteLine($"Id: {person.Id}, Names: {person.Name}, Total age: {person.Age}");
}
774 chars
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main.cs
Id: 1, Names: John, Jack, Total age: 60
Id: 2, Names: Jane, Total age: 30
74 chars
3 lines