Zhang Ming’s family uses 0.5 kg of gas per day, and a bottle of gas can last for 30 days. Zhao Hong’s daily gas consumption is 25% less than Zhang Ming’s. How many days can Zhao Hong's family use the same bottle of gas?
张明家每天用0.5千克煤气，一瓶煤气可以用30天，赵红家每天用的煤气量比张明家少25%．同样的一瓶煤气，赵红家可以用多少天？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">0.5 * (3/4)</gadget>
<output>0.375</output>

<gadget id="calculator">30 / 0.375</gadget>
<output>80</output>

<gadget id="calculator">0.5 * 80</gadget>
<output>40</output>

<result>40</result>