(2/5) of a number is 12, what is its 20%.
一个数的(2/5)是12，它的20%是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">12 / (2/5)</gadget>
<output>30</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 * (1/5)</gadget>
<output>6</output>

<result>6</result>