Complex sentence: The conductor of the train collected passenger tickets at their seats, when Plessy told the conductor he was 7/8ths white and 1/8th black he was advised he needed to move to a "colored's only car".
Split into simpler sentences: The conductor of the train collected passenger tickets at their seats. When Plessy told the conductor he was 7/8ths white and 1/8th black, he was advised he needed to move to a "colored's only car".