During the National Day, all books in Yueshu Store will be sold at a 20% discount. Ding Ding spent 28 yuan to buy a book, how much is the original price of this book.
国庆节期间，悦读书店的书一律八折销售．丁丁花28元买了一本书，这本书原价多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">28 / (4/5)</gadget>
<output>35</output>

<result>35</result>