user: Question: What is the mean Evaluation number (Before April 2009) when the percentage of negative evaluations was 0.8% and the mean Evaluation number of April 2009 was 4.2?
Columns: ['Evaluation average (From February 2011)', 'Evaluation average (From April 2009)', 'Evaluation average (Before April 2009)', '% of negative evaluations', 'Submitting schedule on time', 'Punctuality/Attendance issues', 'Peak lessons taught']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [4.7, '4.6', '4.6', '0.3%', 'Always', 'None', 80.0]
SQL:

assistant: SELECT "Evaluation average (Before April 2009)" FROM "Table" WHERE "% of negative evaluations" = '0.8%' AND "Evaluation average (From April 2009)" = '4.2';