Xinhua Bookstore bought a batch of storybooks, 500 in total, and after selling some, there were 3 packs left, each with 25 books. How many were sold?
新华书店购进了一批故事书，共500本，卖出一些后，还剩3包，每包25本，卖出了多少本？
<gadget id="calculator">25 * 3</gadget>
<output>75</output>

<gadget id="calculator">500 - 75</gadget>
<output>425</output>

<result>425</result>