If a book is sold at 50 yuan each, the profit can be 25%; if the profit is 40%, then how much should each book be sold at.
一种书如果每本按50元出售，可盈利25%；若想盈利40%，那么每本应按多少元出售．
<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">50 / (5/4)</gadget>
<output>40</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">40 * (7/5)</gadget>
<output>56</output>

<result>56</result>