user: Question: What is the total enrollment for an affiliation of public, and was founded before 1866?
Columns: ['School', 'Location', 'Founded', 'Affiliation', 'Enrollment', 'Nickname', 'Primary conference']
Types: ['text', 'text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['Drexel University', 'Philadelphia, PA', 1891.0, 'Private/Non-sectarian', 17000.0, 'Dragons', 'Colonial Athletic Association ( D-I )']
SQL:

assistant: SELECT SUM("Enrollment") FROM "Table" WHERE "Affiliation" = 'public' AND "Founded" < 1866.0;