Xiaoying read a storybook. She originally planned to read 30 pages a day, and finished it in 8 days. She actually read 10 pages less a day. How many days did she actually spend more than planned? (Solution with proportional knowledge)
小英读一本故事书，原计划每天读30页，8天读完，实际每天少读10页，实际比计划多用了多少天？(用比例知识解)
<gadget id="calculator">30 * 8</gadget>
<output>240</output>

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

<gadget id="calculator">240 / 20</gadget>
<output>12</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>