user: Question: What was the Sat 21 Aug time for the rider whose Tues 24 Aug time was 20' 38.40 109.680mph?
Columns: ['Rank', 'Rider', 'Sat 21 Aug', 'Mon 23 Aug', 'Tues 24 Aug', 'Wed 25 Aug', 'Thurs 26 Aug', 'Fri 27 Aug', 'Sat 28 Aug']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Michael Dunlop 997cc Suzuki XR69', 'Untimed Practice', "24' 28.12 92.518mph", "21' 12.70 106.725mph", "19' 40.12 115.097mph", "19' 11.80 117.927mph", "18' 55.78 119.590mph", "22' 47.27 99.3435mph"]
SQL:

assistant: SELECT "Sat 21 Aug" FROM "Table" WHERE "Tues 24 Aug" = '20'' 38.40 109.680mph';