Table:
text: Mathnet
Season 5 (1992)
Season 5 (1992)
Number_in_series Number_in_season Title Directed_by Original_air_date Production_code
26 1 The Case of the Mystery Weekend Bill Schreiner September 21–25, 1992 50021–50025
27 2 The Case of the Smart Dummy Bill Schreiner September 28–October 2, 1992 50231–50235
28 3 The Case: Off the Record Bill Schreiner October 5–9, 1992 50011–50015
29 4 The Case of the Bermuda Triangle Jesus Salvador Treviño October 12–16, 1992 50251–50255
30 5 The Case of the Piggy Banker Bill Schreiner October 19–23, 1992 50241–50245

Question: Which serial number has the production code 50021-50025 on Mathnet?