Duplicates in Google Sheets

Question

I am using Google sheets and I am trying to concatenate multiple column A values in Column C, when and if Column B has a duplicate:

Sample data:

     Column A    Column B           Column C
  1    1247       Santa Fe          1250/1150
  2    1250       Santa Fe          1247/1150
  3    1258       North Shore       1354
  4    1341       Hogan             1255
  5    1255       Hogan             1341
  6    1354       North Shore       1258
  7    1150       Santa Fe          1247/1250

Here, Column C needs to have multiple concatenated values of A, corresponding to the duplicates in column B.

Answer 1

C1:

=JOIN("/",FILTER($A$1:$A$7,$B$1:$B$7=B1,ROW($B$1:$B$7)<>ROW(B1)))

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