book, read 9 pages a day, has been read for 4 days, and there are 25 pages left. How many pages does this book have?
一本书，每天看9页，已经看了4天，还剩下25页．这本书共有多少页？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<gadget id="calculator">36 + 25</gadget>
<output>61</output>

<result>61</result>