CREATE TABLE table_name_90 (winning_score VARCHAR, margin_of_victory VARCHAR)

For the tournament ending with a margin of victory of 6 strokes, what was the winning score?
SELECT winning_score FROM table_name_90 WHERE margin_of_victory = "6 strokes"
SELECT "winning_score" FROM "table_name_90" WHERE "6 strokes" = "margin_of_victory"