At a used book sale, Miss Chen bought a box of 20 assorted books for $40. What was the cost per book
To find the cost per book, we divide the total cost by the number of books:
$40 / 20 books = $ <<40/20=2>>2 per book. Answer: \boxed{2}.
$40 / 20 books = $ <<40/20=2>>2 per book. Answer: \boxed{2}.