The third grade held a book donation activity, one class every three years, every 43 books donated were packed into a pack, 15 packs were packed, and 40 books were left. How many books did Class Three donate?
三年级举行捐书活动，三年一班，捐的书每43本包成一包，包了15包，还剩40本．三年一班捐了多少本书？
<gadget id="calculator">43 * 15</gadget>
<output>645</output>

<gadget id="calculator">645 + 40</gadget>
<output>685</output>

<result>685</result>