The books in the store can be discounted by 20% with the discount card. Xiao Ming bought a set of books with the discount card and saved 5.6 yuan. How much is the original price of this book?
店的图书凭优惠卡可打八折，小明用优惠卡买了一套书，省了5.6元．这套书原价多少钱？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5.6 / (1/5)</gadget>
<output>28</output>

<result>28</result>