A book is priced at 15 yuan per volume, and the profit can be 25%. If the profit is 40%, how much should the price be?
一种书每册定价15元，可盈利25%，如盈利40%，则定价应为多少元．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">15 / (5/4)</gadget>
<output>12</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">12 * (7/5)</gadget>
<output>84/5 = around 16.8</output>

<result>84/5 = around 16.8</result>