Untitled

public class Teacher
{
    Guid Id;
    string Name;
    public decimal Salary;
    public ICollection<Course> Courses;

}
public class Course
{
    Guid Id;
    string Name;
    public Guid TeacherId;
    public Teacher Teacher;
}

public class TeacherDto
{
    public string Name;
    public decimal Salary;
    public ICollection<CourseDto> Courses;
}

public class CourseDto
{
    string Name;
    public TeacherDto Teacher;
}