user: Question: When the Winning score is 74-68-67-75=284, what was the Margin of victory?
Columns: ['Date', 'Tournament', 'Winning score', 'To par', 'Margin of victory', 'Runner(s)-up']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Nov 28, 1971', 'Sea Pines Heritage Classic', '68-73-68-70=279', '−5', '1 stroke', 'Bob Lunn']
SQL:

assistant: SELECT "Margin of victory" FROM "Table" WHERE "Winning score" = '74-68-67-75=284';