(2/5): y=2:1.
(2/5)：y=2：1．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 2</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>