user: Question: What is the firefox value with a 1.8% opera on 30 July 2007?
Columns: ['Date', 'Internet Explorer', 'Firefox', 'Safari', 'Opera']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['October 2013', '27.8%', '16.0%', '13.1%', '2.3%']
SQL:

assistant: SELECT "Firefox" FROM "Table" WHERE "Opera" = '1.8%' AND "Date" = '30 July 2007';