SELECT AVG("Partners\u2003") FROM table_64052 WHERE "Rank\u2003" < '71' AND "Largest U.S. City\u2003" = 'philadelphia' AND "Other" > '77'
What is the average number of partners for the firm with a rank under 71, other over 77, and largest city of Philadelphia?
CREATE TABLE table_64052 (
    "Rank\u2003" real,
    "Largest U.S. City\u2003" text,
    "Total" real,
    "Partners\u2003" real,
    "Other" real
)