How to Run Linq Query in .Net to Get Subjectwise Average Score of a Student of Current Month.
 

        public GetCalculatePerform(int? Student_ID, int? CourseID, int? SemID)
        {

            var newlist1 = dbcontext.Stu_Result
                           .Where(u => u.CourseID == CourseID && u.SemID == SemID)
                           .ToList();
            var scoreCard = (from i in newlist1
                             group i by new { i.SubjectID, i.CourseID } into j
                             select new UserRankObject
                             {
                                 SubjectID = j.Key.SubjectID,
                                 //UnitID = j.Key.UnitID,
                                 //CourseID = j.Key.CourseID,
                                 //MarksScored = j.GroupBy(a => a.UnitID).SelectMany(g => g.OrderByDescending(d => d.).Take(1)).FirstOrDefault()
                                 AverageScore = j.Average(u => u.ScoredMarks)
                             }).ToList().FirstOrDefault();
}



            this.tempobj = scoreCard;

RID	UserID	CourseID	SemID	SubjectID	UnitID	ScoredMarks	TotalMarks	No_Attempts	CreatedDate	
2	1004	109	        124	      2006	        100	    50	    100	         1      	 2019-04-11  
3	1004	109	        124       2006	        100	    60	    100	         1	         2019-04-11 
8	1004	109	        124	      2006	        101	    70	    100	         1	         2019-04-11 
9	1004	109	        124       2006	        103	    40	    100	         1	         2019-02-22
58	1004	109	        124	      2006	        100	    80	    100	         1	         2019-03-30 
59	1004	109	        124       2007	        100	    90	    100	         1	         2019-04-05 
60	1004	109	        124	      2007	        101	    60	    100	         1	         2019-04-05  
79	1004	109	        124	      2007	        101	    74	    100	         1	         2019-04-06 
80	1004	109	        124	      2007	        100	    48	    100	         1	         2019-04-11  
81	1004	109	        124	      2007	        101	    68	    100	         1	         2019-04-11   

Explanation:

2006: on 11/04/2019 average is (60+70)=65    note : 50 is discarded if same unit id found select max value.

2007: : 05/04/2019 average is (90+60)=75 

2007: 06/04/2019 average is (74)

2007: 11/04/2019 average is (48+68)=58

remaining data is not belongs to April(Current) month so discard that 

Expected Output:

subjectid:2007 average: 75 date : 05/04/2019

subjectid: 2007 average: 74 date : 06/04/2019

subjectid: 2006 average: 65 date : 11/04/2019

subjectid: 2007 average: 58 date : 11/04/2019