user: Question: What was the margin of victory when the winning score was –10 (70-72-68-68=278)?
Columns: ['Date', 'Tournament', 'Winning score', 'Margin of victory', 'Runner(s)-up']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Nov 22, 1964', 'Cajun Classic Open Invitational', '–7 (72-70-68-67=277)', '5 strokes', 'Gay Brewer , Jack Nicklaus']
SQL:

assistant: SELECT "Margin of victory" FROM "Table" WHERE "Winning score" = '–10 (70-72-68-68=278)';