The current price of a pair of leather shoes is 50 yuan per pair, and the original price is 40 yuan per pair. By what percentage has the price of these leather shoes been raised?
一种皮鞋现价是每双50元，原价是每双40元．这种皮鞋提价了百分之几？
<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 40</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>