user: Question: Name the duration for  Vladimir Vasyutin , Alexander Volkov
Columns: ['Expedition', 'Crew', 'Launch date', 'Flight up', 'Landing date', 'Flight down', 'Duration (days)']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Salyut 7 – EO-1', 'Anatoli Berezovoy , Valentin Lebedev', '13 May 1982 09:58:05 UTC', 'Soyuz T-5', '10 December 1982 19:02:36 UTC', 'Soyuz T-7', '211.38']
SQL:

assistant: SELECT "Duration (days)" FROM "Table" WHERE "Crew" = 'Vladimir Vasyutin , Alexander Volkov';