CREATE TABLE table_54907 ("From" TEXT, "Adult Rate" TEXT, "Development Rate" TEXT, "16-17 Year Olds Rate" TEXT, "Apprentice Rate" TEXT)

What was the adult rate when the 16-17 year old rate was 3.40?
SELECT "Adult Rate" FROM table_54907 WHERE "16-17 Year Olds Rate" = '£3.40'
SELECT "Adult Rate" FROM "table_54907" WHERE "16-17 Year Olds Rate" = '£3.40'