user: Question: What is the date of the Last Ballet Style Performance of Rhys Kosakowski as Billy Elliot?
Columns: ['Status', 'Name', 'First Performance', 'Last Performance', 'Style']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Original Cast', 'Rhys Kosakowski', '13 November 2007', '19 April 2009', 'Ballet']
SQL:

assistant: SELECT "Last Performance" FROM "Table" WHERE "Style" = 'Ballet' AND "Name" = 'Rhys Kosakowski';