Recently, the webmaster of our website is going to treat guests. 60% of the guests are men, and 70% of the guests are under 30 years old. What is the minimum proportion of men under 30 years old to all men?
最近我们站的站长要请客了，其中60%的客人是男性，而且70%的客人不到30岁，那不到30岁的男性占全部男性的比例最少是多少呢．
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(3/5) * (7/10)</gadget>
<output>21/50 = around 0.42</output>

<result>21/50 = around 0.42</result>