Xinhua Bookstore sold a batch of children's books. After 80% of the sales, another 745 books were shipped. This is 25 more books than the books sold. How many children's books were there?
新华书店出售一批儿童读物，卖出80%后，又运来745本，这是现有的数比卖出的本书还多25本，原来儿童读物多少本？
<gadget id="calculator">745 - 25</gadget>
<output>720</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">720 / (4/5)</gadget>
<output>900</output>

<result>900</result>