In addition to my previous post, where I was calculating age based on birthdates. If we go the other way around and pretend that we have an age span instead; an age 'from' and 'to' we can easily convert those to represent the datespan that we are interested in the following way.

public class Agespan
{
    public int AgeFrom { get; set; }
    public int AgeTo { get; set; }
 
    public DateTime DateFrom 
    {     get 
        { 
            { 
                return DateTime.Now.Date
                .AddYears(-AgeTo - 1)
                .AddDays(1); 
            }
        } 
    }
    public DateTime DateTo     
    { 
        get 
        { 
            return DateTime.Now.Date
            .AddYears(-AgeFrom)
            .AddHours(23)
            .AddMinutes(59)
            .AddSeconds(59); 
        } 
    }
}


Now we can in instantiate our "Agespan" object and use our dates on the object instead.

var agespan = new Agespan { AgeFrom = 24, AgeTo = 55 };