A story book has 300 pages, and Xiaoling reads 30 pages every day. After reading it for a week, how many pages are left?
一本故事书有300页，小玲每天看30页，看了一个星期后，还剩下多少页没看？
<gadget id="calculator">30 * 7</gadget>
<output>210</output>

<gadget id="calculator">300 - 210</gadget>
<output>90</output>

<result>90</result>