user: ### NOW ANSWER:
Question: What is the Diameter (km) of the Valle with a Longitude of 152.5e named before 1997?
Columns: ['Name', 'Latitude', 'Longitude', 'Diameter (km)', 'Year named']
Types: ['text', 'text', 'text', 'real', 'real']
Sample row: ['Ahsabkab Vallis', '24.0S', '79.0E', 700.0, 2000.0]
SQL:

assistant: SELECT MAX("Diameter (km)") FROM "Table" WHERE "Longitude" = '152.5e' AND "Year named" < 1997.0;