Rising 2007 anti-virus software is sold at a 25% discount. The original price is 30 yuan. How much is the current price cheaper than the original price?
瑞星2007版杀毒软件打七五折销售后，原价是30元，现价比原价便宜多少元？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">30 * (1/4)</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>