What page in The Great Gatsby does it say that Gatsby gained his money through criminal activity?

The book does not come out-right and say that he's involved in criminal activity. It is hinted however because Gatsby refuses to say how he made his money, and when you meet Meyer Wolfshiem it is said that he is the one who fixed the World Series. So from Gatsby's contacts we can infer that he is a bootlegger (someone who bring alcohol down from Canada). Alcohol was illegal because of the Prohibition.