Xiao Ming reads a 300-page story book, and reads 20 pages a day for the first 3 days. If the rest read 10 more pages a day, how many days will it take to finish reading?
小明看一本300页的故事书，前3天每天看20页．如果剩下的每天多看10页，还要几天看完？
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">300 - 60</gadget>
<output>240</output>

<gadget id="calculator">20 + 10</gadget>
<output>30</output>

<gadget id="calculator">240 / 30</gadget>
<output>8</output>

<result>8</result>