A story book has 80 pages. Xiao Ming reads 5 pages every day for 7 days. How many pages are left?
一本故事书有80页，小明每天看5页，看了7天，还剩多少页没看？
<gadget id="calculator">5 * 7</gadget>
<output>35</output>

<gadget id="calculator">80 - 35</gadget>
<output>45</output>

<result>45</result>