using static System.Console;

using System.Collections.Generic;

​

public class Program {

    public static void Main(string[] args) {

        var vizu = new Aluno() {

            Nome = "Joao Vizu",

            Ra = "N300361",

            NotaB1 = 7.5M,

            NotaB2 = 10M

        };

        var lais = new AlunoTecnologo() {

            Nome = "Lais Silva",

            Ra = "545454",

            NotaB1 = 7.5M,

            NotaB2 = 10M,

            NotaPim = 9M

        };

        var dao = new AlunoDao();

        dao.Adicionar(vizu);

        dao.Adicionar(lais);

        foreach (Aluno aluno in dao.Listar()) WriteLine($"Nome: {aluno.Nome}\tNotaB1: {aluno.NotaB1}\tNotaB2: {aluno.NotaB2}\tMedia: {aluno.Media}");

    }

}

​

public class Aluno {

    public string Nome { get; set; }

    public string Ra { get; set; }

    public decimal NotaB1 { get; set; }

    public decimal NotaB2 { get; set; }

    public virtual decimal Media => (NotaB1 + NotaB2) / 2;

}

​

 public class AlunoTecnologo : Aluno {

    public decimal NotaPim { get; set; }

    public override decimal Media => NotaPim * 0.2m + base.Media;

}

​

public class AlunoDao {

    private List<Aluno> alunos;

    public AlunoDao() => alunos = new List<Aluno>();

    public void Adicionar(Aluno aluno) => alunos.Add(aluno);

    public List<Aluno> Listar() => new List<Aluno>(alunos);

}