SELECT "Losing bonus" FROM table_39091 WHERE "Try bonus" = '10'
When the try bonus was 10 what was the losing bonus?
CREATE TABLE table_39091 (
    "Club" text,
    "Played" text,
    "Drawn" text,
    "Lost" text,
    "Points for" text,
    "Points against" text,
    "Tries for" text,
    "Tries against" text,
    "Try bonus" text,
    "Losing bonus" text,
    "Points" text
)