The original cost of producing a machine part is 20 yuan, but it only costs 15 yuan after the technological innovation. How much is the cost of this kind of part reduced?
生产一种机器零件，原来的成本是20元，技术革新后只用15元，这种零件的成本降低了百分之几？
<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<gadget id="calculator">5 / 20</gadget>
<output>1/4 = around 0.25</output>

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