user: Question:  how many mean elevation with lowest point being Gulf of Mexico and state being Texas
Columns: ['State', 'Highest point', 'Highest elevation', 'Lowest point', 'Lowest elevation', 'Mean elevation']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Alabama', 'Cheaha Mountain', 'ft m', 'Gulf of Mexico', 'sea level', 'ft m']
SQL:

assistant: SELECT COUNT("Mean elevation") FROM "Table" WHERE "Lowest point" = 'Gulf of Mexico' AND "State" = 'Texas';