CREATE TABLE table_36392 ("Date" CLOB, "Visitor" CLOB, "Score" CLOB, "Home" CLOB, "Decision" CLOB, "Attendance" FLOAT, "Series" CLOB)

How many Attendances that has a Visitor of philadelphia on may 20?
SELECT AVG("Attendance") FROM table_36392 WHERE "Visitor" = 'philadelphia' AND "Date" = 'may 20'
SELECT AVG("Attendance") FROM "table_36392" WHERE "Date" = 'may 20' AND "Visitor" = 'philadelphia'