The original price of a piece of clothing is 120 yuan, and the current price is 90 yuan on sale in a shopping mall. What is the discount rate for this piece of clothing?
一件衣服原价120元，现商场促销，现价为90元，问这件衣服折扣率是多少？
<gadget id="calculator">120 - 90</gadget>
<output>30</output>

<gadget id="calculator">30 / 120</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(1/4) * 1</gadget>
<output>1/4 = around 0.25</output>

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