CREATE TABLE table_15211 ("Date" TEXT, "Visitor" TEXT, "Score" TEXT, "Home" TEXT, "Decision" TEXT, "Attendance" FLOAT, "Record" TEXT)

Decision of parent, and a Home of philadelphia, and a Record of 20 16 7 is on what date?
SELECT "Date" FROM table_15211 WHERE "Decision" = 'parent' AND "Home" = 'philadelphia' AND "Record" = '20–16–7'
SELECT "Date" FROM "table_15211" WHERE "Decision" = 'parent' AND "Home" = 'philadelphia' AND "Record" = '20–16–7'