Wang Dong wants to read a 420-page book. He has already read 180 pages, and the rest will take 10 days to finish. How many pages do he read on average every day?
王东要看一本420页的书，已经看了180页，剩下的需要10天看完，平均每天看多少页？
<gadget id="calculator">420 - 180</gadget>
<output>240</output>

<gadget id="calculator">240 / 10</gadget>
<output>24</output>

<result>24</result>