Yes, the answer to the question, as posted, is certainly not B (it should be E). My only guess is that the question means to say:

"Over a holiday weekend, a certain car dealer sold

4/5 of the cars on its lot. If the cars sold for an average of $6,000 each, how many cars were on the dealer’s lot at the beginning of the weekend?"

But as it stands, there's no way to know how many cars are left at the end of the weekend.

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