A book originally had 320 pages, with 500 words per page, but when it was republished, it was changed to 400 words per page. How many pages more than the original book when it was republished?
一本书原有320页，每页500个字，重新出版时改为每页400个字，这本书重新出版时比原来多几页？
<gadget id="calculator">320 / 400</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">500 * (4/5)</gadget>
<output>400</output>

<gadget id="calculator">400 - 320</gadget>
<output>80</output>

<result>80</result>