Mr. Zhang bought a copy of "Primary School Mathematics Test Before the Primary School Mathematics Exam" with a 22% discount on the Xinhua Bookstore, which was 1.8 yuan cheaper. How much is the original price of this book?
张老师凭会员卡在新华书店，以八八折购买了一本《小学数学考前一搏》，便宜了1.8元，这本书原价多少元．
<gadget id="calculator">88 / 100</gadget>
<output>22/25 = around 0.88</output>

<gadget id="calculator">1 - (22/25)</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">1.8 / (3/25)</gadget>
<output>15</output>

<result>15</result>