There are 140 story books in the library, and the number of science and technology books is 6 times that of story books. How many fewer storybooks are there than tech books?
图书馆有故事书140本，科技书是故事书的6倍．故事书比科技书少多少本？
<gadget id="calculator">140 * 6</gadget>
<output>840</output>

<gadget id="calculator">840 - 140</gadget>
<output>700</output>

<result>700</result>