A story book has 480 pages, and Xiaoya plans to read 24 pages a day. Due to reviewing for the exam, she actually reads 4 pages less a day. How many days later does Xiaoya finish the book?
一本故事书有480页，小亚计划每天看24页，由于复习考试，实际每天少看4页，小亚实际晚几天看完这本书？
<gadget id="calculator">24 - 4</gadget>
<output>20</output>

<gadget id="calculator">480 / 20</gadget>
<output>24</output>

<gadget id="calculator">480 / 24</gadget>
<output>20</output>

<gadget id="calculator">24 - 20</gadget>
<output>4</output>

<result>4</result>