(1/4) of a certain number is 10, what is 30% of this number?
某数的(1/4)是10，这个数的30%是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">10 / (1/4)</gadget>
<output>40</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">40 * (3/10)</gadget>
<output>12</output>

<result>12</result>