Feel free to try the solution below:

1. Go to /Controllers/StudentExamController.cs

2. Go to this function: public IQueryable<ExamViewModel> ReadStudentExams(string status)

3. Edit the code inside else if (status == "past"), change it to:

   else if (status == "past")
   {
       list = (from t1 in db.Exams.AsNoTracking()
               join t2 in db.StudentExams on t1.Id equals t2.ExamId
               let totalQuestion = db.ExamQuestions.Where(a => a.ExamId == t1.Id).Count()
               where (t1.StartDate <= now && t1.EndDate <= now)
               && t2.StartedOn != null && t2.StudentId == currentUserId
               select new ExamViewModel
               {
                   Id = t1.Id,
                   Name = t1.Name,
                   Duration = t1.Duration,
                   StartDate = t2.StartedOn,
                   StartDateIsoUtc = t2.IsoUtcStartedOn,
                   EndDate = t2.EndedOn,
                   EndDateIsoUtc = t2.IsoUtcEndedOn,
                   StudentExamStatus = "Past",
                   TotalQuestions = totalQuestion,
                   Result = t2.Result ?? 0
               }).Distinct();
   }
   

4. Done! Hope it helps. Thank you.

Result: