user: Question: For Amazon.com's device with a weight of 221g (7.8oz) how many screen pixels does the device have?
Columns: ['Maker', 'Model', 'Intro year', 'Screen size (inch)', 'Self-lit', 'Screen type', 'Weight', 'Screen pixels', 'Touch screen', 'micro SDHC']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Aluratek', 'Libre Ebook Reader Pro', '2009', '5', 'no', 'ePaper', '213g (7.5oz)', '600 × 800', 'No', 'up to 32 GB']
SQL:

assistant: SELECT "Screen pixels" FROM "Table" WHERE "Maker" = 'Amazon.com' AND "Weight" = '221g (7.8oz)';