A factory manufactures a part. Due to the updated technology, the cost is reduced from 40 yuan to 30 yuan. How much is the cost reduced?
某工厂制造一种零件，由于更新技术，成本从40元降低到30元，成本降低了百分之几？
<gadget id="calculator">40 - 30</gadget>
<output>10</output>

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

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