static void Main(string[] args) { var buEvaluation = new BasicUsersEvaluation { Id = 1, User = "******", Description = "Good city to visit", Grade = 3 }; var puEvaluation = new PrimeUsersEvaluation { Id = 2, User = "******", Description = "Good city to visit", Grade = 4 }; var service = new EvaluationService <CityEvaluation>(); service.content.Evaluations.Add(buEvaluation); service.content.Evaluations.Add(puEvaluation); Console.WriteLine($"Type of evaluation: {service.GetTypeOfEvaluation()}"); Console.WriteLine($"The final evaluation is {service.CalculateEvaluationAverage()}"); Console.ReadKey(); }