On Children's Day, bookstores cut prices by 25% to sell children's books, and Xiaodong bought a book for 9 yuan. How much is the original price of this book?
六一儿童节这天，书店降价25%出售儿童读物，小东用9元买了一本书．这本书原价是多少元．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">9 / (3/4)</gadget>
<output>12</output>

<result>12</result>