user: Question: What is the winning score of the match with a margin of 3 strokes?
Columns: ['Year', 'Championship', 'Winning score', 'Margin', 'Runner(s)-up']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1979.0, 'Peter Jackson Classic', '−7 (75-70-70-70=285)', '3 strokes', 'Nancy Lopez']
SQL:

assistant: SELECT "Winning score" FROM "Table" WHERE "Margin" = '3 strokes';