Complex sentence: He and Jerry Lewis were partners as the immensely popular comedy team Martin and Lewis then afterwards, he was a member of the "Rat Pack" and a star in concert stages, nightclubs, recordings, motion pictures, and television.
Split into simpler sentences: He and Jerry Lewis were partners in the immensely popular comedy team Martin and Lewis. He was a member of the "Rat Pack" and a star in concert stages, nightclubs, recordings, motion pictures, and television.