Second-hand products in GDP

I am aware that secondhand goods are not counted in GDP due to double counting issues, but I want to ask about a specific case of transaction of second-hand goods.

For instance, what if a student buys a book for 20$, uses the book for a bit, and then sells it to a college bookstore for 40$? And what if the college bookstore sells that used book to another

student for 50$? I know that for the second case, the 10 $$(50$$ - 40$) will be counted in

GDP because this represents the bookstore's services created for providing

books.

But what about the first scenario, where a student sold the book to the

bookstore for 40 $? Would the 20 $$(40$$ - 20$) be counted in GDP? Or would

this just count as the increase in the student's wealth?

Its because the student did not produce any value added in the production of the book. She used the book and then basically transferred it to the bookstore. On the other hand, the bookstore may repair the book and sell it for a \$10 profit. (the bookstore may be advertising, displaying, and other services). The \$10 reflects this additional value added in the economy in the current year, and is thus added to the current GDP.