Complex sentence: She went to Paris to study art in 1921 and there she first met first met Marcel Duchamp in 1923 at a ball given in her honor by Mariette Mills, the mother of a close friend.
Split into simpler sentences: She went to Paris to study art in 1921. She met first met Marcel Duchamp in 1923 at a ball given in her honor by Mariette Mills, the mother of a close friend.