user: Question: What is the highest S ÷ D with a 2420 (220) [3H] paroxetine and an N ÷ D less than 393.8?
Columns: ['[ 3 H]CFT', '[ 3 H]Nisoxetine', '[ 3 H]Paroxetine', 'N ÷ D', 'S ÷ D']
Types: ['real', 'text', 'text', 'real', 'real']
Sample row: [89.1, '3298 (1986)', '1045 (45)', 37.01, 11.79]
SQL:

assistant: SELECT MAX("S ÷ D") FROM "Table" WHERE "[ 3 H]Paroxetine" = '2420 (220)' AND "N ÷ D" < 393.8;