user: ### NOW ANSWER:
Question: What's the 1851 when 1881 had 764?
Columns: ['Year', '1851', '1861', '1871', '1881']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Year', '1851', '1861', '1871', '1881']
SQL:

assistant: SELECT "1851" FROM "Table" WHERE "1881" = '764';