(4/5) of a number is 20, what is 20% of this number.
一个数的(4/5)是20，这个数的20%是多少．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 / (4/5)</gadget>
<output>25</output>

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

<gadget id="calculator">25 * (1/5)</gadget>
<output>5</output>

<result>5</result>