Table schema:
CREATE TABLE table_name_78 (runner_s__up VARCHAR, margin_of_victory VARCHAR, winning_score VARCHAR)

Question: Which runner(s)-up had a Winning score of –13 (68-70-66-71=275) and a Margin of victory of 3 strokes?
SQL: SELECT runner_s__up FROM table_name_78 WHERE margin_of_victory = "3 strokes" AND winning_score = –13(68 - 70 - 66 - 71 = 275)