Table schema:
CREATE TABLE table_name_88 (modern_equivalent VARCHAR, province_of_silla VARCHAR, post_1009_province VARCHAR, administrative_district VARCHAR)

Question: What kind of Modern equivalent has a Post-1009 province of gyeongsang -do, and a Administrative district of jinju -mok, and a Province of Silla of gangju?
SQL: SELECT modern_equivalent FROM table_name_88 WHERE post_1009_province = "gyeongsang -do" AND administrative_district = "jinju -mok" AND province_of_silla = "gangju"