2% of 40 tons weighs the same as how many tons (1/4).
40吨的2%，与多少吨的(1/4)一样重．
<gadget id="calculator">2 / 100</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">40 * (1/50)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(4/5) / (1/4)</gadget>
<output>16/5 = around 3.2</output>

<result>16/5 = around 3.2</result>