The school donates books to Project Hope. The third grade donated 256 books, the fourth grade donated twice as many books as the third grade, and the fifth grade donated 300 books less than the total number of books donated by the third and fourth grades. How many books did the fifth grade donate?
学校为希望工程捐书．三年级捐了256本，四年级捐的书是三年级的2倍，五年级捐的书比三、四年级捐书的总数少300本，五年级捐了多少本书？
<gadget id="calculator">256 * 2</gadget>
<output>512</output>

<gadget id="calculator">256 - 300</gadget>
<output>-44</output>

<gadget id="calculator">512 + (-44)</gadget>
<output>468</output>

<result>468</result>