Apple vendors

Three persons go to the fair to sell their apples. The first person had 10 apples, the second one had 20, and the third one had 30. They all sell them for the same price, and sell all their produce. In the end, they all end up with $10.

What was the asking price?

The asking price was $1 for a single apple, and $2 for a dozen.

That way, the first person sold 10 apples at $1 = $10
The second sold 1 Dozen at $2 and 8 apples at $1 = $10
The thirds sold 2 Dozen at $2 and 6 apples at $1 = $10