Hi Linda,
I don't think the quiz and the textbook are contradictons - they are asking the question differently. The deductible is $100 per car, up to $500 per occurrence. The quiz is asking, if there are nine vehicles involved in a loss, how much will the insurer pay? The insurer will pay $400. If the question asks how much is paid by the insured, the answer is $500.
I hope this helps. Please let me know if you have other questions.
Jan