Complex sentence: Tom asserts that he and Daisy have a history that Gatsby could never understand, and he announces to his wife that Gatsby is a criminal whose fortune comes from bootlegging alcohol and other illegal activities.
Split into simpler sentences: Tom asserts that he and Daisy have a history that Gatsby could never understand. In addition to that, he announces to his wife that Gatsby is a criminal whose fortune comes from bootlegging alcohol and other illegal activities.