The bookstore shipped a batch of storybooks. 30% of the total was sold on the first day, 35% of the total was sold on the second day, and 25 more copies were sold on the second day than on the first day. How many books are there in total?
书店运来一批故事书．第一天卖出总数的30%，第二天卖出总数的35%，第二天比第一天多卖出25本．这批书一共有多少本？
<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(7/20) - (3/10)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">25 / (1/20)</gadget>
<output>500</output>

<result>500</result>