A book has 45 pages in total. Xiaohong reads 8 pages every day for 4 days. How many pages are left?
一本书一共有45页，小红每天看8页，看了4天，还剩多少．
<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">45 - 32</gadget>
<output>13</output>

<result>13</result>