If a book is priced at 10 yuan each and the profit is 25%, what is the purchase price?
一种书，若定价每本10元，盈利25%，则进价为多少元．
<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">10 / (5/4)</gadget>
<output>8</output>

<result>8</result>