Table: web_browser_usage
Columns: date
internet_explorer
firefox
safari
opera

Question: What percentage of browsers were using Internet Explorer during the period in which 27.85% were using Firefox?
SQL: SELECT "internet_explorer" FROM web_browser_usage WHERE "firefox" = '27.85%'

Question: What percentage of browsers were using Internet Explorer in April 2009?
SQL: SELECT "internet_explorer" FROM web_browser_usage WHERE "date" = 'april 2009'

Question: What percentage of browsers were using Safari during the period in which 31.27% were using Firefox?
SQL: SELECT "safari" FROM web_browser_usage WHERE "firefox" = '31.27%'

Question: What percentage of browsers were using Opera in October 2010?
SQL: SELECT "opera" FROM web_browser_usage WHERE "date" = 'october 2010'

Question: What percentage of browsers were using Opera in November 2009?
SQL: SELECT "opera" FROM web_browser_usage WHERE "date" = 'november 2009'