user: Question: When 1509 is the c/w 15+ how many results of 15 to 17 are there?
Columns: ['C/W 15+', 'Oblast\\Age', '15 to 17', '18 to 19', '20 to 24', '25 to 29', '30 to 34', '35 to 39', '40 to 44', '45 to 49', '50 to 54', '55 to 59', '60 to 64', '65 to 69', '70+']
Types: ['real', 'text', 'real', 'text', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real']
Sample row: [1736.0, 'Belgorod', 24.0, '160', 599.0, 1203.0, 1528.0, 1821.0, 1906.0, 1941.0, 1903.0, 1836.0, 1857.0, 1971.0, 2139.0]
SQL:

assistant: SELECT COUNT("15 to 17") FROM "Table" WHERE "C/W 15+" = 1509.0;