CREATE TABLE table_55789 ("Ordinary income rate" TEXT, "Long-term capital gain rate" TEXT, "Short-term capital gain rate" TEXT, "Long-term gain on commercial buildings*" TEXT, "Long-term gain on collectibles" TEXT)

What long-term gain for collectibles coincides with ordinary income rate 15%?
SELECT "Long-term gain on collectibles" FROM table_55789 WHERE "Ordinary income rate" = '15%'
SELECT "Long-term gain on collectibles" FROM "table_55789" WHERE "Ordinary income rate" = '15%'