A storybook has 280 pages. Fangfang has been reading it for 5 days, with an average of 40 pages per day. How many pages are left in this storybook?
一本故事书有280页，芳芳已经看了5天，平均每天看40页，这本故事书还剩下多少页？
<gadget id="calculator">40 * 5</gadget>
<output>200</output>

<gadget id="calculator">280 - 200</gadget>
<output>80</output>

<result>80</result>