A Google Sheet is being used to insert markings for students tests.
When a single test is done by students, teacher assigns multiple grades for it. For instance, one marking for writing, one for comprehension, etc.
The sheet should finally build columns containing an average for all the markings assigned within the same date.
For instance, in the above sheet (link here), columns with markings given on December 16th (cols B,G,M,R,V) should be averaged in column AE.
How could I use VLOOKUP or MATCH to lookup all markings in a given row, where the date in row# 3 is "16-12"?? Do I need QUERY/IMPORTRANGE?