A book is sold at a 30% discount, which is 2.4 yuan cheaper than the original price. How much is the original price of this book?
一本书打七折销售，比原价便宜了2.4元，这本书的原价是多少元？
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">2.4 / (3/10)</gadget>
<output>8</output>

<result>8</result>